Case 4 - Audition

Question 1

1. What are some of the social consequences of hearing loss?
2. What are some of the psychological consequences of hearing loss?
3. What aspects of social exclusion do they suffer from?

Answer 1

1. Social and behavioral difficulties, dependency, restricted opportunities
2. Victims of abusive language, higher levels of stress, higher levels of mental health problems
3. Social isolation, lack of education, and poverty

Question 2

1. What is attention?
2. What are the 3 elements of attention?
3. What is alerting?
4. What is orienting?
5. What is selection?

Answer 2

1. Selecting for active processing of specific aspects of your environment
2. Alerting, orienting, and selection
3. Change in internal state of individual in preparation for perceiving a stimulus
4. Selection of information from sensory input i.e. moving towards the target etc.
5. Choosing among multiple conflicting actions or responses

Question 3

1. What are the 4 different types of attention?
2. What is sustained attention?
3. What is Selective attention?
4. What is alternating attention?
5. What is divided attention?

Answer 3

1. Sustained attention, selective attention, alternating attention, divided attention
2. Ability to keep focus for long periods of time even if exposed to repetitive actions or activity e.g. learning
3. Selecting aspects when confronted with multiple stimuli
4. Ability to switch or transfer focus from one activity to another
5. Ability to focus on 2 or more stimuli simultaneously

Question 4

Define the following:

• Sound
• Frequency
• Hertz
• Pitch
• Intensity(Amplitude)

Answer 4

• Variations in air pressure which are audible
• Number of compressed pathces that pass by an object (ear) each second
• Number of cycles per second
• Tone - determined by the frequency
• Difference in pressure between compressed and rarefied patches of air. Determines loudness.

Question 5

1. What is the range of sound humans can hear?

Answer 5

1. 20Hz to 20,000Hz

Question 6

Identify the following:

• Pinna
• Auditory canal
• Ossicles (M,I,S)
• Oval window
• Cochlea
• Tympanic membrane
• Round window
• External acoustic meatus
• Helix
• Antihelix
• Auricular lobe
• Semicircular canals
• Eustachian tube
• CN VIII

1. Where is each found?

Answer 6

Outer ear

• Pinna
• Auditory canal

Middle ear

• Ossicles (M,S,I)

Inner ear

• Oval window
• Cochlea
• Tympanic membrane
• Round window

Question 7

1. What moves in the ear to start the process of audition?
2. After the TM is moved what happens?
3. What do the Ossicles do to sound waves?
4. Which is larger the TM or the oval window?

Answer 7

1. Tympanic membrane
2. Ossicles vibrate, and move the oval window
3. Amplify them
4. Tympanic membrane

Question 8

1. What is the attenuation reflex?
2. Which muscles are involved?
3. Why do we need the attenuation reflex?
4. Is it instantaneous?

Identify:

• Stapedius muscle
• Tensor tympani muscle

Answer 8

1. Muscle contraction in the middle ear, making the ossicles rigid.
2. Tensor tympani & Stapedius muscles
3. To protect the inner ear from damage
4. No, takes time so damage can occur with fast and very loud sound

Question 9

1. What is the function of the eustachian tube?
2. How is it kept closed?
3. What can be done to equalise middle ear pressure?

Answer 9

1. To maintain the pressure in the middle ear, as it is continuous with the nasal cavities
2. Valve
3. Yawning or swallowing - opens the ET

Question 10

In the inner ear, identify:

• Oval window
• Round window
• Scala vestibuli - what does this contain?
• Scala media - what does this contain?
• Reissners membrane
• Basilar membrane
• Scala tympani - What does this contain?
• Helicotrema - what is this?
• Organ of Corti
• Tectorial membrane
• Stria Vascularis
• Spiral ganglion

Answer 10

Scala vestibuli & tympani - contain perilymph

Scala media - contains endolymph

Helicotrema - Where the scala tympani becomes continous with the scala vestibuli

Question 11

1. What makes endolymph and periplymph different?
2. What maintains the ionic content?

Answer 11

1. Endolymph has a high K+ content
   
   1. Perilymph has a high Na+ content
2. Stria vascularis

Question 12

1. Where is the base of the basilar membrane?
2. Which part of the basilar membrane is wider?
3. Which part is more stiff?
4. Movement of which fluid causes the BM to bend?
5. High frequency waves cause what?
6. Low frequency waves cause what?
7. What does this establish for the brain?

Identify:

• Base of basilar membrane
• Apex of basilar membrane

Answer 12

1. Base is closest to the oval window
2. Apex
3. Base
4. Endolymph
5. Base of the membrane vibrates a lot, dissipates energy
6. Wave travels all the way to the apex, before energy dissipated
7. Tonotopy - place code

Question 13

In the organ of corti, identify:

• Outer hair cells
• Inner hair cells
• Rods of corti - what is their function?
• Supporting cells
• Spiral ganglion
• CN VIII

Answer 13

Rods of corti - provide structural support

Question 14

1. What happens in the organ of corti?
2. What do hair cells do?
3. What are hair cells (Type of cell)?
4. How is sound transduced?

Answer 14

1. Where auditory receptor cells (Hair cells) are found
2. Convert mechanical energy into change in membrane potential
3. Specialised epithelial cells
4. Bending of hair stereocilia leads to sound transduction

Question 15

On the hair cells, identify:

• Stereocilia
  1. What differentiates inner hair cells from outer hair cells?

Answer 15

1. IHC - stereocilia are just below the tectorial membrane
   
   1. OHC - stereocilia are within the tectorial membrane

Question 16

1. What do the hair cells synapse with?
2. What does CN VIII project to?

Answer 16

1. Spiral ganglion
2. Cochlear nuclei in Medulla (Brainstem)

Question 17

1. Movement of which membrane is necessary for transduction?
2. What is found on the tip of the hair cells?
3. Which position makes it generate a hair receptor potential?

Answer 17

1. Basilar membrane
2. Specialised ion channel, which opens and closes by bending of sterocilia
3. Ion channel is open

Question 18

1. What does movement of the tip link lead to?
2. What ion moves into the cell?
3. What does this lead to?
4. What NT is released? To what cell?

Answer 18

1. Increased tension, and rate of channel openings
2. K+ (Depolarisation)
3. Activation of Ca+ voltage gated channels - entry of Ca+
4. Glutamate - to the spiral ganglion cells

Question 19

1. When the movement of the tip link is in the opposite direction?
2. What does this lead to?
3. What happens to the ions?
4. What kind of channel is the tip link channel?

Answer 19

1. Relieves tension on tip link
2. Channels spend more time closed
3. Reduced inward movement of K+
4. Mechanically gated (Physically opened)

Question 20

1. How many hair cells does a spiral ganglion synapse with? (Inner and outer)
2. How do OHC’s amplify sounds?
3. What are the 2 motor proteins?

Answer 20

1. Inner - 1 hair cell, Outer - Numerous
2. Motor proteins change length of the hair cells to amplify the movement of the basilar membrane
3. Prestin & Myosin

Question 21

1. Where do the afferents from the spiral ganglion go?
2. Which nuclei do they go to? On which side?

Answer 21

1. Via CN VIII to the medulla
2. Ipsilateral cochlear nuclei (Dorsal & Ventral)

Question 22

1. Where do the axons from the ventral cochlear nucleus go to?
2. Where do the olivary nuclei axons go?
3. Where is the inferior colliculus?

Answer 22

1. Superior olivary nucleus bilaterally
2. via Lateral leminiscus to the Inferior colliculus
3. Midbrain

Question 23

1. Where do the axons of the Dorsal cochlear nucleus go?
2. Where does the inferior colliculus send axons to?
3. Where is this found?

Answer 23

1. straight to the inferior colliculus of midbrain
2. Medial geniculate nucleus
3. Thalamus

Question 24

1. Where does the MGN project to?
2. What are the accessory projections?

Answer 24

1. Auditory cortex (Temporal lobe)
2. Superior colliculus & Cerebellum

Question 25

1. How are the inner hair cells selective? 2. What is the characteristic frequency?

Answer 25

1. They are found at a particular location on the basilar membrane, and only fire AP's in response to sound in a limited frequency range 2. Frequency that the neurons are most responsive to

Question 26

1. How is stimulus intensity coded? (2) 2. What do more intense stimuli cause? 3. What is loudness percieved correlated with?

Answer 26

1. Firing rate of neurons and number of active neurons 2. More intense stimulus causes more BM vibration and so increased membrane potential change 3. Number of active hair cells as more are activated

Question 27

1. What frequencies are characteristic of the apical basilar membrane? 2. What frequencies are characteristic of the basal basilar membrane?

Answer 27

1. Low frequency 2. High frequency

Question 28

1. What is Tonotopy?

Answer 28

1. Different frequencies lead to different maximal deformations of the basilar membrane so this allows for recognition of frequency

Question 29

1. What is created in the cochlear nuclei by tonotopy? 2. What is phase locking?

Answer 29

1. Organised pattern based on characteristic frequencies 2. Consistent firing of a cell at the same phase as the sound wave

Question 30

1. When do phase locked neurons fire AP's? 2. What is the maximal level for phase locking? 3. What happens after this level? 4. What is then used?

Answer 30

1. At peaks or troughs of the waves, to convey the timing of the wave 2. 5000 Hz 3. AP's generated randomly as too fast for AP's to represent timing 4. Tonotopy

Question 31

1. What is Interaural time delay? 2. When is this not effective?

Answer 31

1. Localisation based on the time at which the sound arrives in each ear 2. When the sound frequency is so high that 1 cycle of sound is smaller than distance between ears

Question 32

1. What is interaural intensity difference? 2. What is the frequency the human ear is most sensitive to?

Answer 32

1. Using the head shadow to locate sound, used for higher frequency sounds 2. 2000 to 5000 Hz

Question 33

1. What is the function of the vestibular system? 2. What is the function of the otolith organs? 3. What is the function of the semicircular canals?

Answer 33

1. Identify the location of our head in space 2. Detecting linear acceleration 3. Detecting angular acceleration

Question 34

1. What 2 organs make up the Otolith organs? 2. What is the macula? 3. What are Otoconia?

Answer 34

1. Utricle & Saccule 2. Contains hair cells which are used for orientation 3. Crystals of Calcium Carbonate

Question 35

1. Identify: * Macula * Otoconia * Kinocilium

Answer 35

1.

Question 36

1. When force is exerted which direction do the otoconia move? 2. What moves? 3. What does this do to the cilia?

Answer 36

1. Same direction as the force 2. Gelatinous cap 3. Bends them

Question 37

1. What happens when the hair cells are bent toward the kinocilium? 2. What happens when they bend away from the kinocilium? 3. What is significant about each macula?

Answer 37

1. Depolarisation 2. Hyperpolarisation 3. Each one is direction specific, so allows to differentiate movement

Question 38

1. What happens to the hair cells in the opposite ear? 2. What does the Utriccle detect? 3. What does the saccule detect?

Answer 38

1. The hairs bend in the opposite direction, so you have the opposite effect 2. Horizontal acceleration 3. Vertical acceleration

Question 39

1. What is the angle between each semicircular canals? 2. What movements do they detect? 3. What is the organ here called?

Answer 39

1. 90 degrees 2. Pitch, roll, yaw (Rotational movements) 3. Ampulla & Cupulla

Question 40

1. What happens when there is angular movement? 2. What does this cause? 3. What happens when there is deflection towards the kinocilium? And away from it?

Answer 40

1. Endolymph displaces the gelatinous mass displacing the cupula 2. Change in K+ concentration, due to opening or closing of channels 3. Increased firing so increased K+, Decreased firing

Question 41

1. What is NT used by these neurons? 2. What happens when the canal is rotated round its axis?

Answer 41

1. Glutamate 2. Canal and cupula spin, and endolymph stays due to inertia (Exerting force on cupula)

Question 42

Identify: * Crista * Ampulla * Cupula * Kinocilium * Endolymph

Answer 42

Question 43

1. Which movement is perceived by the superior SC? Posterior? Horizontal? 2. Where do the vestibular axons from CN VIII go to? Which side? 3. What are the relevant tracts?

Answer 43

1. Roll, Yaw, Pitch 2. Vestibular nuclei (Ipsilateral) 3. Vestibulospinal tract & Medial longitudinal funinculus

Question 44

1. What is the vestibulo-occular reflex? 2. Which input is it triggered by?

Answer 44

1. Keeps eyes oriented in direction, when body is moving in another 2. Vestibular input

Question 45

1. Where does the afferent signal originate? 2. Where does it go to? 3. Which nerve controls the eye muscle? 4. Which tract is relevant?

Answer 45

1. Scarpa's ganglion 2. Medial vestibular nucleus 3. Abducens nerve (Contralateral) 4. Medial longitudinal fasciculus to CN III

Question 46

1. What is Nystagmus? 2. What would dysfunction in the slow phase mean? 3. What would dysfunction in the fast phase mean?

Answer 46

1. alternatiting slow eye movement, with rapid saccadic movement 2. Lesion in the vestibulo-occular pathway 3. Lesion in the higher brain centers

Question 47

1. What is Menieres disease? 2. What is benign paroxysmal positional vertigo?

Answer 47

1. Increase in endolypmh pressure which causes disruption of signal transduction - Tinnitus, nausea, and nystagmus 2. Disloged otolith which causes vertigo

Question 48

1. Can a person with post lingual deafness hear again with a cochlear implant? 2. Can a person with pre lingual deafness hear again with a cochlear implant?

Answer 48

1. Yes 2. No

Question 49

1. What does the gene DFNB1 lead to? 2. How is it inherited?

Answer 49

1. Non-syndromic hearing loss and deafness, congenital. Causes sensorineural hearing loss 2. Autosomal recessive

Question 50

1. What are the tonsils? 2. What is tonsilitis? 3. Which pathogens usually cause it? 4. Treatments?

Answer 50

1. Lymphoid tissue 2. Inflammation of the pharyngeal tonsils 3. Group A haemolytic streptoccous, or herpes simplex 4. Corticosteroids or Tonsilectomy (If chronic)

Question 51

1. What is otitis media? 2. What is it caused by? 3. Which tonsil can also cause it?

Answer 51

1. Inflammation of middle ear 2. Dysfunction of the eustachian tube due to edema or negative tympanic pressure 3. Enlarged adenoid

Question 52

1. What test is used to measure air conduction? 2. What test is used to measure bone conduction? 3. What dB range is normal hearing?

Answer 52

1. Pure tone audiometry or vibrating tuning fork in front of ear 2. Tuning fork placed on the head 3. 0-25 dB

Question 53

1. What is conductive hearing loss? 2. What is the result? 3. What can cause it?

Answer 53

1. Normal bone conduction, Poor air conduction 2. Reduced effectiveness of air conduction, but doest affect bone conduction as the middle ear can be bypassed 3. OM or blockage of the external auditory meatus

Question 54

1. What is sensorineural hearing loss? 2. What causes it?

Answer 54

1. Bone conduction and air conduction are very close to each other but reduced, higher than 25dB 2. Cochlear abnormalities, or problem with transmission of sound to brain.

Question 55

1. What is mixed hearing loss? 2. What will be the result if tested?

Answer 55

1. Where there is both conductive and sensorineural loss 2. Air conduction is lower than bone conduction, and bone conduction threshold is less than 25dB

Question 56

1. What is a tympanogram? 2. What do the following show? * A * B * C * AD * AS

Answer 56

1. Tests middle ear function, and compliance of the tympanic membrane to changing air pressures * Normal middle ear * Middle ear effusion, blocked * Eustachian tube dysfunction * Highly compliant middle ear system (Flaccid) * Less compliant middle ear system (Less mobility)

Question 57

1. What is the Webers test? 2. What must the patient report? 3. What is a normal result?

Answer 57

1. Place tuning fork in middle of forehead equidistant from ears. 2. Which ear the sound is louder in? 3. Sound is = in both ears

Question 58

1. If the defective ear hears it louder? 2. If the normal ear hears it louder? 3. Can this test be used if the defective ear is not known?

Answer 58

1. Conductive hearing loss in the defective ear 2. Sensorineural hearing loss in the defective ear 3. No, use Rinne's test

Question 59

1. What is the Rinnes test? 2. What is a normal result (Positive)? 3. What is an abnormal result (Negative)?

Answer 59

1. Tuning fork placed on mastoid process behind each ear, when sound not heard. Move outside the ear. Patient reports when they cant hear the sound 2. Sound heard outside ear is louder than head when on bone (AC\>BC) 3. Sound is louder on bone than in air (BC\>AC)

Question 60

1. What is the Rhinne's test used for? 2. What is the Webbers test used for?

Answer 60

1. Conduction testing 2. Localisation of the defect

Question 61

1. What are otoacoustic emissions?

Answer 61

1. Used to check cochlear function, objectively