Final

Question 1

Sound localization

Answer 1

The ability to identify the location of a sound source in the sound field.

Question 2

Precedence effect

Answer 2

When a sound is followed by another sound separated by a sufficiently short time delay (below the listener’s echo threshold), listeners perceive a single auditory event.

Question 3

Auditory stream analysis

Answer 3

The ability to separate each of the sound sources and separate in space.

Question 4

Perceptual grouping

Answer 4

Putting parts together into a whole.

Question 5

Auditory Space

Answer 5

Surrounds an observer and exists wherever there is sound. Tones with the same frequency activate the cochlea (hair cells) in the same way regardless of where they are coming from.

Question 6

Localization cues

Answer 6

Researchers study how sounds are localized in space by using:
Azimuth coordinate: position left to right
Elevation coordinates: position up and down
Distance coordinates: position from observer (most difficult).

Question 7

On average, people can localize sounds:

Answer 7

Directly in front of them most accurately. To the sides behind their heads least accurately. Location cues are not contained in the receptor cells like on the retina in vision; thus, location for sounds must be calculated.

Question 8

Binaural cues

Answer 8

Location cues based on the comparison of the signals are received by the left and right ears. Two binaural cues: interaural time difference and interaural level difference.

Question 9

Interaural time difference (ITD)

Answer 9

Difference between the times that sounds reach the two ears. When distance to each ear is the same, there are no differences in time. When the source is to the side of the observer, the times will differ.

Question 10

Interaural level difference (ILD)

Answer 10

Difference in sound pressure level reaching the two ear. Reduction in intensity occurs for high frequency sounds for the far ear. The head casts an acoustic shadow. This effect does not occur for low frequency sounds.

Question 11

Cone of confusion

Answer 11

The “cone of confusion” describes a specific region where the auditory system has difficulty accurately determining the source of a sound. This occurs because certain cues used for sound localization, such as interaural time differences (ITDs) and interaural level differences (ILDs), become ambiguous within this region.

Question 12

Monaural Cue for Sound Location

Answer 12

ILD and ITD are not effective for judgments on elevation, since in many locations they may be zero. Primary monaural cue for localization is called a spectral cue, because the info for localization is contained in differences in the distribution (or spectrum) of frequencies that reach the ear from different locations.

Question 13

Experiment investigating spectral cues

Answer 13

Listeners were measured for performance locating sounds differing in elevation. They were then fitted with a mold that changed the shape of their pinnae. Right after the molds were inserted, performance was poor for elevation but was unaffected for azimuth. After 19 days, performance for elevation was close to original performance. Once the molds were removed, performance stayed high. This suggests that there might be two different sets of neurons - one for each set of cues.

Question 14

Jeffress Neural Coincidence Model

Answer 14

There are a series of neurons that each respond best to a specific ITD. These neurons are wired so that they each receive signals from the two ears. Signals from the left ear arrive along the blue axon, and signals from the right ear arrive along the red axon. If the sound source is directly in front of the listener, so the sound reaches the left and right ear simultaneously, then signals from the left and right ears start out together. As each signal travels along its axon, it stimulates each neuron in turn. At the beginning, neurons receive signlas from only the left ear or the right ear. When the signals both reach neuron 5 together, that neurons fires. This neuron and the others in this circuit are called coincidence detectors, because they only fire when both signals arrive at the neuron simultaneously.

Question 15

Broadly tuned ITD Neurons

Answer 15

These neurons are specialized for processing interaural time differences (ITDs), which are differences in the time of arrival of a sound at each ear. ITDs are a cue used to localize sounds in the horizontal plane, particularly for low-frequency sounds. Coding for localization based on broadly tuned neurons: in the right hemisphere that respond when sound is coming from the left, in the left hemisphere that respond when sound is coming from the right. The location of a sound is indicated by relative responses of these two types of broadly tuned neurons.

Question 16

Cortical Mechanisms of Location

Answer 16

Area A1 is involved in locating sound: Neff’s research on cats. Posterior belt area is involved in locating sound: Recanzone’s research on monkey neurons. Antereior belt is involved in perceiving sound.

Question 17

What and Where Auditory Pathways

Answer 17

What, or ventral stream, starts in the anterior portion of the core and belt and extends to the prefrontal cortex - used to identify sounds. Where, or dorsal stream, starts in the posterior core and belt and extends to the parietal and prefrontal cortices - used to locate sounds. Evidence from neural recordings, brain damage, and brain scanning support these findings.

Question 18

Hearing Inside Rooms (Direct/indirect sound)

Answer 18

Direct sound: sound that reaches the listener’s ears straight from the source.
Indirect sound: sound that is reflected off of environmental surfaces and then to the listener.
When a listener is outside, most sound is direct; however, inside a building, there is direct and indirect sound.

Question 19

Perceiving Two Sounds that Reach the Ears at Different Times - Experiment by Litovsky et al.

Answer 19

Listeners sat between two speakers: a lead speaker and a lag speaker. When sounds comes from the lead speaker followed by the lag speaker with a long delay, listeners hear two sounds. When the delay is decreased from 5:20msec, listeners hear the sound as only coming from the lead speaker: the precedence effect.

Question 20

Architectural Acoustics

Answer 20

The study of how sounds are reflected in rooms. Factor that affects perception in concert halls - Reverberation time

Question 21

Reverberation time

Answer 21

The time it takes sound to decrease by 1/1000th of its original pressure. If it is too long, sounds are “muddled”, if it is too short, sounds are “dead”, ideal times are around two seconds.

Question 22

Intimacy time

Answer 22

Time between when sound leaves its source and when the first reflection arrives. Best time is around 20ms.

Question 23

Bass ratio

Answer 23

Ratio of low to middle frequencies reflected from surfaces. High bass ratios are best.

Question 24

Spaciousness factor

Answer 24

Fraction of all the sound received by listener that is indirect. High spaciousness factors are best.

Question 25

Auditory scene

Answer 25

The array of all sound sources in the environment.

Question 26

Auditory scene analysis

Answer 26

Process by which sound sources in the auditory scene are separated into individual perceptions. Does not happen at the cochlea since simultaneous sounds are together in the pattern of vibration of the basiliar membrane.

Question 27

Separating Sound Sources: Simultaneous grouping (Onset time, location, timbre and pitch)

Answer 27

Onset time: sounds that start at different times are likely to come from different sources. Location: a single sound source tends to come from one location and to move continuously. Similarity of timbre and pitch: similar sounds are grouped together.

Question 28

Separating Sound Sources: sequential grouping - Experiment by Bregman and Campbell

Answer 28

Compound melodic line in music is an example of auditory stream segregation - the ability to separate different sound sources. Stimuli were in alternating high and low tones. When stimuli played slowly, the perception is hearing high and low tones alternating. When the stimuli are played quickly, the listener hears two streams, one high and one low.

Question 29

Separating Sound Sources: Experiment by Deutsch: the scale illusion or melodic channeling

Answer 29

Stimuli were two sequences alternating between the right and left ears. Listeners perceive two smooth sequences by grouping the sounds by similarity in pitch. This demonstrates the perceptual heuristic that sounds with the same frequency come from the same source, which is usually true in the environment.

Question 30

Separating Sound Sources: Experiment by Warren et al. - A demonstration of auditory continuity, using tones.

Answer 30

Tones were presented interrupted by gaps of silence or by noise. In the silence condition, listeners perceived that the sound stopped during the gaps. In the noise condition, the perception was that the sound continued behind the noise.

Question 31

Separating Sound Sources: Effect of past experience - Experiment by Dowling

Answer 31

Melody "Three Blind Mice" is played with notes alternating between octaves. Listeners find it difficult to identify the song. However, after they hear the normal melody, they can hear it in the modified version using melody schema.

Question 32

Connections Between Hearing and Vision - Visual capture

Answer 32

Visual capture or the ventriloquist effect: an observer perceives the sound as coming from the visual location rather than the source for the sound. Two-flash illusion

Question 33

Hearing and Vision: Physiology - Thaler et al. (2011)

Answer 33

The interaction between vision and hearing is multisensory in nature. They used expert blind echolocators to create clicking sounds and observed that these signals activated the brain.

Question 34

Ian Waterman Story

Answer 34

Worked as an apprentice in a butcher shop. He had previously gotten a small cut in his finger and mostly likely the cut had developed into an infection. What started out as a common cold would prove to be much worse. He gradually lost control over his limbs and ended up lying in bed without conscious control over any part of his body from neck down. His muscles still worked and his brain was receiving signals from his body conveying sensations such as pain and differences in temperature.But the brain seemed to have lost the notion of where the different parts that it was supposed to move were located.

Question 35

Nerve fibre (motor fibre and sensory fibres)

Answer 35

Can be either a sensory fibre or motor fibre. The motor fibres sends signals to our muscle fibres telling them to contract. The sensory fibres starts either in the skin or in the muscle and come in different sizes. The largest ones convey information concerning touch, muscle sensitivity or sense of movement. The smallest ones convey information concerning muscle fatigue, temperature and certain forms of pain.

Question 36

The Somatosensory System 3 parts

Answer 36

Cutaneous senses: perception of touch and pain from stimulation of the skin. Proprioception: ability to sense position of the body and limbs. Kinesthesis: ability to sense movement of body and limbs.

Question 37

Skin

Answer 37

Protects the organism by keeping damaging agents from penetrating the body. Epidermis is the outer layer of the skin, which is made up of dead skin cells. Dermis is below the epidermis and contains mechanoreceptors that respond to stimuli such as pressure, stretching, and vibration.

Question 38

Two types of mechanoreceptors located close to surface of the skin (Merkel and Meissner)

Answer 38

Merkel receptor fires continuously while stimulus is present - responsible for sensing fine details. Meissner corpuscle fires only when a stimulus is first applied and when it is removed - responsible for controlling hand-grip.

Question 39

Two types of mechanoreceptors located deeper in the skin (Ruffini and Pacinian)

Answer 39

Ruffini cylinder fires continuously to stimulation - associated with perceiving stretching of the skin. Pacinian corpuscle fires only when a stimulus is first applied and when it is removed - associated with sensing rapid vibrations and fine texture.

Question 40

Pathways from Skin to Cortex

Answer 40

Nerve fibers travel in bundles (peripheral nerves) to the spinal cord. Two major pathways in the spinal cord: Medial lemniscal pathway and spinothalamic pathway. These cross over to the opposite side of the body and synapse in the thalamus.

Question 41

Medial lemniscal pathway

Answer 41

Consists of large fibers that conveys tactile, proprioceptive, and vibratory sensory information from the body to the brain. Critical role in transmission of fine touch and proprioceptive sensations, allowing individuals to perceive the position, movement, and texture of objects, as well as their own body position and movements.

Question 42

Spinothalamic pathway

Answer 42

Consists of smaller fibers that carry temperature and pain information.

Question 43

The Somatosensory Cortex

Answer 43

Signals travel from the thalamus to the somatosensory receiving area (S1) and the secondary receiving area (S2) in the parietal lobe. Body map (homunculus) on the cortex in S1 and S2 shows more cortical space allocated to parts of the body that are responsible for detail. Plasticity in neural functioning leads to multiple homunculi and changes in how cortical cells are allocated in body parts.

Question 44

Measuring Tactile acuity - Two-point threshold

Answer 44

Minimum separation needed between two points to perceive them as two units

Question 45

Measuring tactile acuity - Grating acuity

Answer 45

Placing a grooved stimulus on the skin and asking the participant to indicate the orientation of the grating.

Question 46

Measuring tactile acuity - Raised pattern identification

Answer 46

Using such patterns to determine the smallest size that can be identified.

Question 47

Receptor Mechanisms for Tactile Acuity - Merkel receptors

Answer 47

There is a high density of Merkel receptors in the fingertips. Merkel receptors are densely packed on the fingertips: similar to cones in the fovea. Both two-point thresholds and grating acuity studies show these results.

Question 48

Cortical Mechanisms for Tactile Acuity

Answer 48

Body areas with high acuity have larger areas of cortical tissue devoted to them. This parallels the "magnification factor" seen in the visual cortex for the cones in the fovea. Areas with higher acuity also have smaller receptive fields on the skin.

Question 49

Pacinian Corpuscle (PC)

Answer 49

Primarily responsible for sensing vibration. Nerve fibers associated with PCs respond best to high rates of vibration. The structure of the PC is responsible for the response to vibration: fibers without the PC only respond to continuous pressure.

Question 50

Spatial vs Temporal Cues

Answer 50

Katz (1925) proposed that perception of texture depends on two cues. Spatial cues: determined by the size, shape, and distribution of surface elements - bumps and grooves. Temporal cues: determined by the rate of vibration as skin is moved across finely textured surfaces - fine textures, could only be perceived as fingers move across the surface. Duplex theory of texture perception: two preceptors may be responsible for this process.

Question 51

Cortical Responses to Surface Texture - Lieber and Sliman Bensmaia (2019)

Answer 51

Cortical neurons that fired best to coarse textures received input from SA1 neurons from the skin (Merkel recpetors). Neurons that fired best to fine textures received input from PC receptors (Pacinian corpuscles).

Question 52

Active touch

Answer 52

Touch in which a person actively explores an object, usually with fingers and hands.

Question 53

Passive touch

Answer 53

Occurs when touch stimuli are applied to the skin, as when two points are pushed onto the skin to determine the two-point threshold.

Question 54

Haptic perception

Answer 54

Perception in which three-dimensional objects are explored with the fingers and hand. A number of different systems are interacting with each other: (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 involved in moving your fingers and hands, (3) the cognitive system, which was involved in thinking about the information provided by the sensory and motor systems.

Question 55

Psychophysical research on object perception

Answer 55

Has shown that people can accurately identify most common objects within 1 or 2 seconds using active touch. People use a number of distinctive movements, which they called exploratory procedures (EPs), and that the types of EPs used depend on the object qualities the participants are asked to judge.

Question 56

Cortical Neurons

Answer 56

Cortical neurons are specialized. Neurons in the ventral posterior nucleus - tactile area of the thalamus, 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.

Question 57

The Cortical Physiology of Tactile Object Perception

Answer 57

In the cortex, we find some neurons with center-surround receptive fields and others that respond to more specialized stimulation of the skin. Neurons in the monkey's somatosensory cortex (e.g, parietal) that respond when the monkey grasps a specific object.

Question 58

Cortical Responding is Affected by Attention - Steven Hsiao and coworkers

Answer 58

Recorded the responses of neurons in areas S1 and S2 to raised letters that were scanned across a monkey's finger Tactile-attention condition: monkey had to perform a task that required focusing its attention on the letters being presented to its fingers. Visual-attention condition, the monkey had to focus its attention on an unrelated visual stimulus.

Question 59

Pain

Answer 59

Pain is a multimodal phenomenon containing a sensory component and an affective or emotional component.

Question 60

Inflammatory pain

Answer 60

Caused by damage to tissue or inflammation of joints or by tumor cells.

Question 61

Neuropathic pain

Answer 61

Caused by lesions or other damage to the nervous system. Examples: carpal tunnel syndrome, which is caused by repetitive tasks such as typing: spinal cord injury; and brain damage due to stroke.

Question 62

Nociceptive pain

Answer 62

Caused by activation of receptors in the skin called nociceptors, which are specialized to respond to the tissue damage or potential or potential damage.

Question 63

Direct pathway model of pain

Answer 63

Pain occurs when nociceptor receptors in the skin are stimulated and send their signals directly from the skin to the brain.

Question 64

Situations in which pain was affected by factors in addition to stimulation of the skin

Answer 64

Soldiers' wounds had a positive aspect: they provided escape from a hazardous battlefield to the safety of a behind-the-lines hospital.

Question 65

Phantom limb

Answer 65

People who have had a libm amputated continue to experience the limb. Signals are sent from the part of the limb that remains after amputation. Cutting the nerves that used to transmit signals from the limb to the brain does not eliminate either the phantom limb or the pain and concluded that the pain must originate not in the skin but in the brain. Cannot be explained by the direct pathway model.

Question 66

Gate Control Model of Pain

Answer 66

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. This model proposes that there are additional pathways that influence the signal sent from the spinal cord to the brain. Central idea is that. the 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.

Question 67

Input to the gate control system occurs along three pathways

Answer 67

S-fibers: The small-diameter fibres are associated with nociceptors. Activity in the S-fibers increases the activity of the transmission cell (T-Cell), so they always excite T-cells, and therefore increase pain. L-fibers: The large-diameter fibres (L-fibers) carry information about nonpainful tactile stimulation. Eg., signals sent from rubbing the skin. Activity in the L-fibers can send inhibition to the T-cells, which closes the gate, which decrease T-cell activity and decreases pain. Central control: These fibres, which contain information related to cognitive functions which as expectation, attention, and distraction, carry signals down from the cortex. Activity coming down from the brain also closes the gate, decreases T-cell activity and decreases pain.

Question 68

Placebo effect

Answer 68

Placebo: a pill that contains no active ingredients. Placebo effect: decrease in pain from a substance that has no pharmacological effect.

Question 69

Effect of Expectation on Pain Ratings

Answer 69

Participants rated the pain in a condition in which a saline solution was presented by infusion (baseline). 3 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 presented (positive expectation) (3) that the drug was going to be discontinued in order to investigate the possible increase in pain that would occur (negative expecation). Nocebo effect: negative effect caused by the negative experience.

Question 70

Top-Down Processes for pain: Attention

Answer 70

One way to decrease pain is to distract a person's attention from the source of the pain

Question 71

Top-Down Processes for pain: Emotions experiments

Answer 71

Minet de Wied and Marinis Verbaten (2001): Viewing positive and negative pictures, hand immersed in cold. Roy and coworkers (2008): Pleasant and unpleasant music, heat stimulus.

Question 72

Five basic taste qualities

Answer 72

salty, sour, sweet bitter, umami: described as meaty, brothy, or savory, and associated with MSG.

Question 73

The chemical sense involve 3 componenents:

Answer 73

Taste: occurs when molecules enter the mouth in solid or liquid form and stimulate receptors on the tongue. Olfaction: occurs when air-borne molecules enter the nose and stimulate receptor neurons in the olfactory mucosa, located on the roof of the nasal cavity. Flavor: the impression we experience from the combination of taste and olfaction and several other factors.

Question 74

Neurogenesis

Answer 74

Constant renewal of the receptors unique to taste and smell - Due to exposure to harmful materials. Cycle of birth, development, and death over 5-7 weeks for olfactory receptors and 1-2 weeks for taste receptors.

Question 75

Anosmia

Answer 75

The loss of the ability to smell as a result of injury or infection. People suffering from this describe the great void created by inability to taste many. foods.

Question 76

Chemical sense as "gatekeepers".

Answer 76

(1) Identify things that the body needs for survival and that should therefore be consumed. (2) Detect things that would be bad for the body and that should therefore be rejected.

Question 77

Emotional components of the Chemical Senses

Answer 77

Things that are bad for us often taste or smell unpleasant. Things that are good for us generally taste or smell good. Smelling an odor associated with a past place or event can trigger memories, which in turn may create emotional reactions.

Question 78

Connections Between Taste Quality and a Substance's Effect - The four taste qualities

Answer 78

Sodium chloride (salty). Hydrochloric acid (sour). Sucrose (sweet). Quinine (bitter). Potassium chloride (KCl) has substantial salty and bitter components. Sodium nitrate (NaNO3) results in a taste consisting of a combination of salty, sour, and bitter.

Question 79

Connections between taste quality and a substance's effect (Sweetness, bitter, salty)

Answer 79

Sweetness is usually associated with substances that have nutritive value. Bitter is usually associated with substances that are potentially harmful. Salty taste indicates the presence of sodium. However, there is not a perfect connection between tastes and functions of substances.

Question 80

Structure of the Taste System - Tongue

Answer 80

The surface of the tongue contains many ridges and valleys caused by the presence of structures called papillae, which fall into 4 categories: Filiform, fungiform, foliate, circumvilliate.

Question 81

Filiform papillae

Answer 81

Are shaped like cones and are found over the entire surface of the tongue, giving it its rough appearance.

Question 82

Fungiform papillae

Answer 82

Are shaped like mushrooms and are found at the tip and sides of the tongue.

Question 83

Foliate Papillae

Answer 83

Are a series of folds along the back of the tongue on the sides.

Question 84

Circumvilliate papillae

Answer 84

Are shaped like flat mounds surrounded by a trench and are found at the back of the tongue.

Question 85

Structure of the Taste System - Taste buds

Answer 85

Taste buds are located in all of the papillae except for the filiform. Tongue contains approx. 10,000 taste buds. Each taste bud has 50-100 taste cells with tips that extend into the taste pore. Transduction occurs when chemicals contact the receptor sites on the tips.

Question 86

Structure of the Taste System - Signals from taste cells travel along a set of pathways.

Answer 86

Electrical signals generated in the taste cells are transmitted from the tongue in a number of different nerves: (1) the chorda tympani nerve (from taste cells on the front and sides of the tongue); (2) the glossopharyngeal nerve (from the back of the tongue); (3) the vagus nerve (from the mouth and throat); (4) the superficial petronasal nerve( from the soft palette - the top of the mouth). The fibers from the tongue, mouth, and throate make connections in the brain stem int he nucleus of the solitary tract, and from there, signals travel to the thalamus and then. to two areas in the frontal lobe: the insula and frontal operculum cortex.

Question 87

Population coding

Answer 87

Quality is signaled by the pattern of activity distributed across many neurons.

Question 88

Population coding experiment by Erickson

Answer 88

Demonstrated population coding. Shocked rats while they were drinking potassium chloride and then gave them a choice between ammonium chloride and sodium chloride. When the rats were shocked for drinking ammonium chloride, they subsequently avoided the potassium chloride, as predicted by the electrophysiological results.

Question 89

Population coding on humans - Erickson (1971)

Answer 89

Asked humans to make similarity judgments between a number of different solutions. Substances that were perceived to be similar were related to patterns of firing for these same substances in the rat. Solutions judged more similar psyco-physically had similar patterns of firing, as population coding would predict.

Question 90

Specificity Coding - Experiment by Mueller et al.

Answer 90

Genetic cloning was used to determine if mice could be created that possessed a human receptor that respond to this substance. The experiment was successful, but not all data show the same results. Used a chemical compound called PTC that tastes bitter to humans but not to mice. Mueller decided to see what would happen if he used genetic cloning techniques to create a strain of mice that had the human bitter-PTC receptor. When he did this, mice with this receptor avoided high concentrations of PTC.

Question 91

Specificity Coding - Recordings from neurons at the beginning of the taste systems of animals

Answer 91

Some neurons are specialized to respond to specific stimuli. Some neurons respond to a number of different types of stimuli.

Question 92

Specificity Coding - Applying Amiloride to the tongue

Answer 92

Blocks flow of sodium to taste receptors. Causes decrease in the responding of neurons in rat's brainstem that respond to salt, but not to those that respond to salty and bitter.

Question 93

Individual Differences in Taste (PTC and PROP)

Answer 93

There are different responses to PTC and PROP. Tasters, non tasters, and super tasters: Tasters have more taste buds than non tasters, tasters have specialized receptors for these compounds, super tasters appear more sensitive to bitter substances than tasters. The presence of specialized receptors: Genes on human chromosomes that are associated with taste and smell receptors. PROP and PTC tasters have specialized receptors that are absent in non tasters.

Question 94

Macrosmatic

Answer 94

Many animals are macrosmatic: having a keen sense of smell that is necessary for survival.

Question 95

Microsmatic

Answer 95

Humans are microsmatic: a less keen sense of smell that is not crucial to survive.

Question 96

The detection threshold of odors

Answer 96

The detection threshold for odors is the lowest concentration at which an odor can be detected.

Question 97

Measuring the detection threshold for odors

Answer 97

Yes/no procedure: participants are given trials with odors along with "blank" trials. They respond by saying yes or no. This can result in bias, in terms of when the participant decides to respond. Forced-choice: two trials are given, one with odorant and one without. Participant indicates which smells strongst.

Question 98

Sensitivity of different species to odors

Answer 98

Rats are 8 to 50 times more sensitive to odors than humans. Dogs are 300 to 10,000 times more sensitive. However, individual receptors for all of these animals are equally sensitive. The difference lies in the number of receptors they each have - Humans have ten million and dogs have one billion olfactory receptors. Humans can discriminate more than one trillion different odors, but find it difficult to identify odors, only successful half of the time.

Question 99

The Puzzle of Olfactory Quality

Answer 99

Researchers have found it difficult to map perceptual experience onto physical attributes of odorants: there is no specific language for odor quality, some molecules that have similar structure smell different, and some that have different structures smell the same. Links have been found between the structure of molecules, olfactory quality, and pattersn of activation in the olfactory system.

Question 100

The Olfactory Mucosa

Answer 100

Olfactory mucosa is located at the top of the nasal cavity. Odorants are carried along the mucosa coming in contact with the olfactory receptor neurons (ORN). These neurons contain molecules called olfactory receptors. Humans have about 350 types of receptors; each have a protein that crosses the membrane seven times.

Question 101

Processing odors

Answer 101

Perceiving odor objects involves olfactory processing that occurs in two stages: (1) takes place at the beginning of the olfactory system in the olfactory mucosa and olfactory bulb, involves analyzing - in this stage, the olfactory sytem analyzes the different chemical components of odors and transforms these components into neural activity at specific places in the olfactory bulb. (2) takes place in the olfactory cortex and beyond, involves synthesizing.

Question 102

Signals from the olfactory bulb are sent to:

Answer 102

Primary olfactory (priform) cortex in the temporal lobe and amygdala - amygdala plays a role in emotional reactions to odors. Then to secondary olfactory (orbitofrontal) cortex in the frontal lobe.

Question 103

How Odorants are Represented in the Piriform Cortex - Experiment by Rennaker

Answer 103

Used multiple electrodes to measure neural responding in the piriform cortex, and found that isoamyl acetate causes activation across the cortex. (a) Odor object: Odorant molecules --> (b) Olfactory bulb: Chemotopic map activated --> (c) Piriform cortex: Scattered activation --> (d) Piriform cortex after learning: Pattern for odor object.

Question 104

How odor objects are represented - Experiment by Wilson

Answer 104

Measured response of neurons in the rat's piriform cortex to two odorants. A mixture: isoamyl acetate and peppermint. A compound: isoamyl acetate alone. Results showed that with enough exposure, the piriform cortex could discriminate between the mixture and the compound. He concluded that, given enough time, neurons in the piriform cortex can learn to discriminate between different odors, and that this learning may be involved in our ability to tell the difference between different odors in the environment.