Week 6 (How do we hear, taste, and smell?)

Question 1

What are the properties of sound

Answer 1

-Frequency & Pitch
-Amplitude & Loudness
-Complexity & Timbre

Question 2

What is Frequency & Pitch

Answer 2

Rate of vibration n cycles per second (Hertz, Hz)

Question 3

What is Amplitude & Loudness

Answer 3

Intensity of sound (Decibels, Db)

Question 4

What is Complexity & Timbre

Answer 4

Complexity determines Timbre, (e.g. difference between violin and flute)

Question 5

What are the three sections of the ear?

Answer 5

Outer ear, Middle ear, Inner ear

Question 6

What are the components of the outer ear?

Answer 6

Pinnae: Funnel-like structure channels sound into ear.

Ear canal: Narrowing amplifies sound waves toward membrane (tympanic membrane)

Question 7

What are the components of the middle ear?

Answer 7

Osssicles:
-Malleus (Hammer)
-Incus (Anvil)
Stapes (Stirrup)

Question 8

What are the components of the inner ear?

Answer 8

Cochlea:
-Converts vibrational energy into waves of fluid
-The auditory part of the vestibulocochlear nerve

Inner ear includes vestibular apparatus.

Question 9

Structure and function of the Cochlea

Answer 9

-Coiled structure, bony exterior, hollow compartments, filled with fluid.
-Vibrations from the ossicles to oval window membrane sends waves through fluid filled cochlea.

-Vibration is transmitted to organ of court via basilar membrane (structures in cochlea)
-Movement in sensory hair cells transduce sound waves into neural activity, which is sent along auditory nerve to the brain.

Question 10

Structure and function of the tonotopic basilar membrane.

Answer 10

The basilar membrane vibrates when stapes moves the fluids of the inner ear. Different sound wave frequencies cause peak pending f the membrane at different points along its length.

Question 11

What does the Organ of Corti

Answer 11

Sends vibrations to auditory nerve.

Question 12

What is the auditory pathway to the brain?

Answer 12

-Ear (cochlea)
-Cochlear nuclei (brainstem)
-Superior olive (brainstem)
-Inferior Colliculi (midbrain)
-Medial geniculate nucleus (thalamus)
-Auditory cortex (Temporal cortex

Question 13

Where are the primary and secondary auditory cortex located?

Answer 13

Primary:
Located in the temporal lobe, within the Heschl’s gyrus, within the Sylvia fissure, tonotopic.

Secondary:
-Surrounds primary auditory cortex,

Question 14

What allows us to hear pitch

Answer 14

Tonotopic organisation in the basilar membrane.

Question 15

What allows us to hear loudness

Answer 15

Louder sounds produce larger pressure changes, produces more intense basilar vibration.

Question 16

How do we detect location

Answer 16

-Difference in timing in each ear
-Relative loudness

Detected by nuclei in the brainstem that receive input from both left and right ventral cochlear nuclei.

-Superior olive (medial part) neurons respond to difference in arrival time between each ear.

-Superior olive (lateral part) and trapezoid body neurons respond to differences in loudness.

Question 17

Two types of deafness

Answer 17

Conduction deafness
-Pathology of the outer/middle ear: prevent vibrations reaching cochlear

Sensorineural deafness/ hearing loss
-Originate from cochlear or nerve lesions
-Cochlear losses most common

Question 18

Damage to auditory cortex

Answer 18

Left primary auditory cortex damage:
-Deficit in differentiating speech sounds

Right primary auditory cortex damage
-Deficit in discriminating musical sounds

Bilateral auditory cortex damage
-Agnosia for sound (everything sounds the same)

Question 19

Fancy word for smell

Answer 19

Olfaction

Question 20

Olfactory segment

Answer 20

-Along the roof of the nasal cavity
-Lined with the olfactory epithelium, which contains receptors for smell.

Question 21

Olfactory receptors

Answer 21

Each olfactory receptor has a short thick dendrite, ending in 10 to 20 cilia, that projects into a mucous layer (olfactory mucosa)
-Chemicals in air dissolve into mucosa to interact with cilia

Question 22

Olfactory bulbs

Answer 22

Receptor cells project to olfactory bulbs

Theolfactory nervesare non-myelinatedand consist of bundles of slenderfibresheldtogether by thin strips of connectivetissue; form olfactory cranial nerve

Receptors form synapses with dendrites of mitral cells at glomeruli
Mitral cells send axons from olfactory bulb to a broad range of forebrain areas

Question 23

Path from olfactory bulbs to the brain.

Answer 23

Mitral cells send axons from olfactory bulb to a broad range of forebrain areas
Amygdala & pyriform cortex have no connection through thalamus
Orbitofrontal cortex (role in emo & social behaviours) has thalamic connection

Question 24

Abnormalities of olfaction

Answer 24

Anosmia (absence of the sense of smell)
-Can be anosmic for certain odours
-Can be temporary or permanent

Hyposmia (diminished olfactory sensitivity)
-Hyposmia might be very early sign of Parkinson’s disease

Dyosmia (distorted sense of smells)
-Misinterpreted smells of hallucination of smells

Question 25

The tongue

Answer 25

Covered in papillae and taste buds

Question 26

What are the different taste senses?

Answer 26

Sweet, salty, sour, bitter, umami

Question 27

Taste pathways to the brain

Answer 27

Pathway one: -Through posterior medulla to ventroposterior medial nucleus of thalamus Then through two sub pathways -one to primary somatosensory cortex (tactile information ) -one to gustatory cortex of insult (flavour) Pathway two: -projects through pons to hypothalamus & amygdala Hypothesised to play a role in feeding behaviour.