BMB 1 - Visual & Auditory Pathways

Question 1

True/False.

Images projected onto the retina are inverted from right to left and also upside down in order to create our perceived visual experience.

Answer 1

True.

(Think of the retina as an anterior-facing cup, and then imagine the way light rays from below hit the upper portion and from the left side hit the right side, etc.)

Question 2

True/False.

The majority of the visual sensation from the left eye goes to the right visual cortex, and the majority of the visual sensation from the right eye goes to the left visual cortex.

Answer 2

False.

Visual sensation from the left hemispheres of both eyeballs goes to the left visual cortex (stimuli from the right), and visual sensation from the right hemispheres of both eyeballs goes to the right visual cortex (stimuli from the left).

Question 3

The left visual field projects to the _______ visual cortex.

The right visual field projects to the _______ visual cortex.

Answer 3

The left visual field projects to the right visual cortex.

The right visual field projects to the left visual cortex.

Question 4

Light from the _______ (right/left) side of the body hits the _______ (right/left) retinas and is transmitted to the right visual cortex.

Answer 4

Light from the left side of the body hits the right retinas and is transmitted to the right visual cortex.

Question 5

Light from the _______ (right/left) side of the body hits the _______ (right/left) retinas and is transmitted to the left visual cortex.

Answer 5

Light from the right side of the body hits the left retinas and is transmitted to the left visual cortex.

Question 6

Which retinal sections send afferent fibers to the right visual cortex?

Answer 6

The left eye nasal and right eye temporal portions

(i.e. the right hemispheres of both eyes)

Question 7

Which retinal sections send afferent fibers to the left visual cortex?

Answer 7

The right eye nasal and left eye temporal portions

(i.e. the left hemispheres of both eyes)

Question 8

What two factors give the macula such a high visual acuity?

Answer 8

(1) 1:1 ratio of cones to bipolar neurons
(2) 100% cones (no rods present)

Question 9

Identify the fovea and optic nerve within this image:

Answer 9

Question 10

Where (generally speaking) is the blind spot found on the retinal surface?

(I.e. where is the optic nerve found within the retina?)

Answer 10

The nasal retina

Question 11

Optic nerves project to the optic _________, where fibers from the _________ (nasal/temporal) retina crisscross.

Answer 11

Optic nerves project to the optic chiasm, where fibers from the nasal retina crisscross.

Question 12

Optic nerves lead to the optic chiasm, from which optic ________ lead to the ________ ________ nucleus, which projects to area 17 of the visual cortex.

Answer 12

Optic nerves lead to the optic chiasm, from which optic tracts lead to the lateral geniculate nucleus, which projects to area 17 of the visual cortex.

Question 13

Which portions of the visual field get parsed In the lateral geniculate nucleus?

Answer 13

Upper, lower and macular aspects

Question 14

Describe the auditory pathway starting in the cochlea and ending in the primary auditory cortex.

Answer 14

Cochlea

Cochlear nuclei

Superior olive

Inferior colliculus

Medial geniculate nucleus

Primary auditory cortex

Question 15

What structures help coordinate visual and auditory reflexes?

Answer 15

The superior and inferior colliculi

Question 16

What nerve and muscle aid to protect the ear from extremely loud noises?

Answer 16

CN VII + the stapedius

Question 17

The tonotropy of the auditory pathway is preserved throughout. It typically follows that high frequencies are _________ (medial/lateral).

Answer 17

The tonotropy of the auditory pathway is preserved throughout. It typically follows that high frequencies are medial.

Question 18

What term refers to age-related hearing loss?

Answer 18

Presbycusis

Question 19

Short term exposure at ______ dB causes temporary hearing loss while extended periods or higher can cause permanent hearing loss.

Mean threshold for discomfort = ______ dB (airplane engine).

Threshold for pain = ______ dB (largest air raid siren).

Answer 19

Short term exposure at 100 dB causes temporary hearing loss while extended periods or higher can cause permanent hearing loss.

Mean threshold for discomfort = 120 dB (airplane engine).

Threshold for pain = 140 dB (largest air raid siren).

Question 20

Under normal conditions, what is the relationship between air conductance and bone conductance in normal hearing?

Answer 20

Air > bone

Question 21

In conductive hearing loss, what is the relationship between air conductance and bone conductance in normal hearing?

Answer 21

Bone > air

Question 22

In sensorineuronal hearing loss, what is the relationship between air conductance and bone conductance in normal hearing?

Answer 22

Air > bone

Question 23

Describe the presentation of the Weber test in a patient with conductive hearing loss.

Answer 23

Localization to affected ear

Question 24

Describe the presentation of the Weber test in a patient with sensorineuronal hearing loss.

Answer 24

Localization to unaffected ear

Question 25

For the body to maintain an upright posture, 2 out of the following 3 must be intact:

▪ _______ clues (most important)

▪ ______ impulses from the neck and leg muscles

▪ ______ responses

Answer 25

For the body to maintain an upright posture, 2 out of the following 3 must be intact:

▪ Visual clues (most important)

▪ Proprioceptive impulses from the neck and leg muscles

▪ Vestibular responses

Question 26

Angular acceleration (_______ _______) involves the rotation of the head.

Linear acceleration (_______, _______ ) involves movement in the three (X, Y, Z) planes.

Answer 26

Angular acceleration (semicircular canals) involves the rotation of the head.

Linear acceleration (utricle, saccule ) involves movement in the three (X, Y, Z) planes.