Chapter 4, pt.3

Question 1

What is transduction of sound and where does it occur?

Answer 1

Transduction converts sound vibrations into neural signals within the inner ear, specifically in the cochlea
- a fluid-filled spiral structure responsible for auditory transduction.

Question 2

What is the function of the basilar membrane?

Answer 2

It runs the length of the cochlea and vibrates in a traveling wave when hit by sound, moving the inner hair cells that trigger neural signals.

Question 3

What are inner hair cells?

Answer 3

Specialized auditory receptor neurons in the basilar membrane (part of the Organ of Corti) that bend in response to sound and initiate neural impulses.

Question 4

Describe the auditory pathway from the ear to the brain.

Answer 4

Hair cells → Auditory nerve → Thalamus → Primary auditory cortex (A1), which is topographically organized (low freq = front, high freq = back).

Question 5

What are the main perceptual attributes of sound?

Answer 5

Loudness, pitch, timbre, and location.

Question 6

How is loudness encoded?

Answer 6

By the total amount of hair-cell activity; louder sounds = more activated hair cells.

Question 7

What is Place Code

Answer 7

different frequencies activate different locations along the basilar membrane.

Question 8

What is temporal code

Answer 8

timing of action potentials corresponds to wave peaks.

Question 9

What determines timbre?

Answer 9

The mixture of frequency components and the pattern of hair-cell activation across the basilar membrane.

Question 10

How do we localize sound?

Answer 10

Using monaural (one ear) and binaural (two ears) cues:

Interaural time difference: sound reaches one ear sooner.

Interaural level difference: sound louder in nearer ear due to head shadowing high frequencies.

Question 11

How does the auditory system organize sounds?

Answer 11

Through grouping and segregation — sounds similar in frequency, pitch, loudness, or starting/stopping together are perceived as coming from one source.

Question 12

What are the two main types of hearing loss?

Answer 12

Conductive: damage to eardrum or ossicles.

Sensorineural: damage to cochlea, hair cells, or auditory nerve.

Question 13

What does a cochlear implant do?

Answer 13

Replaces the function of damaged hair cells by electrically stimulating the auditory nerve (best for early-detected sensorineural loss).

Question 14

How do hearing aids work?

Answer 14

Amplify sound; modern ones reduce background noise and adjust to environments using digital processing.

Question 15

What are the main hearing-loss patterns?

Answer 15

Flat: equal loss at all frequencies (often conductive).

Ski slope: high-frequency loss (most common).

Reverse slope: low-frequency loss (rare).

Cookie-bite: mid-frequency loss (speech difficulty).

Reverse cookie-bite: loss at low + high frequencies.

Question 16

What are the somatosenses?

Answer 16

Body senses including touch, pressure, vibration, temperature, and pain from receptors in skin, muscles, and joints.

Question 17

What is haptic perception?

Answer 17

Active exploration of the environment by touching and grasping with the hands.

Question 18

What are mechanoreceptors and thermoreceptors?

Answer 18

Mechanoreceptors: respond to pressure, texture, or vibration.

Thermoreceptors: detect temperature changes (warm/cold).

Question 19

What is a tactile receptive field?

Answer 19

The small skin area where a receptor responds to stimulation.

Question 20

What does contralateral control mean in touch?

Answer 20

The left side of the body maps to the right brain hemisphere and vice versa.

Question 21

What and where pathways in touch?

Answer 21

“What” → object properties (texture, shape).

“Where” → spatial location and movement.

Question 22

What are the two types of pain fibres?

Answer 22

A-delta: fast, sharp pain.

C fibres: slow, dull pain.

Question 23

What are the two pain pathways?

Answer 23

Sensory/discriminative → somatosensory cortex (type/location).

Emotional/motivational → amygdala, hypothalamus, frontal lobe (unpleasantness, escape drive).

Question 24

What is referred pain?

Answer 24

Pain from internal organs felt on the skin due to shared spinal neurons.

Question 25

What is the gate-control theory?

Answer 25

Pain signals in the spinal cord can be inhibited (“gated”) by feedback from the brain or nearby sensory neurons.

Question 26

What brain structure modulates pain?

Answer 26

Periaqueductal grey (PAG) in the midbrain—activated by endorphins to suppress pain signals.

Question 27

How can perception of pain change?

Answer 27

It’s subjective—affected by mood, attention, motivation, and expectations.

Question 28

What is proprioception?

Answer 28

Sense of body and limb position.

Question 29

What is the vestibular system?

Answer 29

Three semicircular canals near the cochlea that detect head movement and work with vision to maintain balance.

Question 30

What are the two chemical senses and their stimuli?

Answer 30

Olfaction (smell): airborne molecules. Gustation (taste): molecules dissolved in saliva.

Question 31

Describe the process of smell transduction.

Answer 31

Odorants → olfactory receptor neurons (ORNs) in olfactory epithelium → olfactory bulb → brain regions under frontal lobes.

Question 32

What are pheromones?

Answer 32

Biochemical odorants that communicate information between members of the same species (social/reproductive roles). Humans lack a functional VNO; evidence for human pheromones remains limited.

Question 33

What are the five (or six) basic tastes?

Answer 33

Salt, sour, bitter, sweet, umami (savory), and possibly fat (oleogustus).

Question 34

What are taste buds and where are they found?

Answer 34

Organs of taste transduction, 5,000–10,000 located on the tongue, palate, and throat.

Question 35

Are taste receptors localized to tongue regions?

Answer 35

No – all basic tastes are detected wherever taste buds are located (no true “taste map”)

Question 36

What are tasters, nontasters, and supertasters?

Answer 36

Categories of individuals differing in taste-bud density and sensitivity to bitter compounds.

Question 37

What is flavour perception?

Answer 37

A multisensory experience combining taste, smell, texture, and even visual and auditory cues (e.g., food colour influences taste).

Question 38

What is multimodal processing?

Answer 38

The brain combines information from multiple senses; vision gives high spatial acuity, hearing gives high temporal acuity.

Question 39

What is bottom-up processing?

Answer 39

Perception starting from raw sensory input; data-driven (e.g., exploring a new object).

Question 40

What is top-down processing?

Answer 40

Perception guided by prior knowledge, expectations, and context (e.g., recognizing objects in the dark).