Exam 2

Question 1

The BUGs (Brotherhood of Unpleasant Gnats) has “hatched” a plan to render humans incapable of stopping their bites. To do so they need to stop people from focusing their eyes on small objects near their faces. Eliminating which component of the eye will stop us from focusing on close annoying bugs while still allowing us to focus on objects far in the distance?

Answer 1

Lens

Question 2

The chairman of the BUGs discovers that there is one problem with their “project no focus” plan – they have no clue how to accomplish it. Their new idea is to deactivate the human retina in a way that makes people blind only in the far peripheral (monocular) portion of the left visual field. The pests will zoom in for a bite from that side. What portion of which retina needs to be destroyed to make the people blind in only the left peripheral (monocular) field?

Answer 2

Left eye nasal retina

Question 3

The vice-chairman of the BUGs gently points out to the chairman that they also don’t know how to damage part of the retina. A subcommittee studies the problem and decides that stopping all visual transduction is required. To do this, they target the one step in transduction in which light directly activates a molecule. Light directly activates:

Answer 3

Rhodopsin

Question 4

A lot of the BUGs infantry got swatted when the “stop transduction project” failed. The gnats make one last attempt by recruiting the assistance of their friends the fireflies. The idea is to figure out adaptation and prevent the human retina from adapting to the sudden increase in light level that occurs when all the fireflies light up at the same time. Which of the following is a fundamental role that calcium plays in light adaptation?

Answer 4

Inhibition of guanylyl cyclase

Question 5

All the following are consequences of the photoreceptor distribution on the human retina EXCEPT
a) Acuity is better at night (scotopic light) using the peripheral retina than the fovea
b) Color is best during the day (photopic light) using the central retina
c) The majority of all photoreceptors are in the fovea
d) There is a spot on the nasal retina without any photoreceptors

Answer 5

The majority of all photoreceptors are in the fovea

Question 6

The primary direct target of axons from the konio layers of the LGN is which layer of primary visual cortex?

Answer 6

Layer 2/3

Question 7

A commando unit of the gnats from question 1 makes its way into a person’s LGN where they set up camp. They get really hungry one night and eat all the neurons in layer 3 of the left LGN. They felt bad about that, but a gnat’s gotta eat. Which of the following would be the most likely result of the loss of layer 3 of the left LGN?

Answer 7

Reduced ability to discriminate red/green borders of objects seen in the left eye

Question 8

All the following statements about the LGN are true EXCEPT
a) It fires in an intrinsic bursting mode during sleep
b) It receives most of its input from retinal ganglion cells
c) It plays a role in paying attention to visual objects of interest
d) The axons leaving the LGN make up the optic radiation

Answer 8

It receives most of its input from retinal ganglion cells

Question 9

You are studying a retinal circuit in which there are two cones, one directly connected to a bipolar cell (cone 1) and a second cone that is connected to cone 1 via a horizontal cell (cone 2). By recording with an electrode you determine that the bipolar cell has an on-center off-surround receptive field. If both cones are initially in the dark, what happens when you then shine light on cone 1 (leaving cone 2 in the dark)?

Answer 9

The bipolar cell depolarizes because it has a metabotropic glutamate receptor

Question 10

With the same circuit as in the previous question, light is moved to hit cone 2 and cone 1 is now in the dark. As a result, all the following changes occur EXCEPT
a) Cone 1 will release more glutamate than in question 9
b) The bipolar cell will be more depolarized than in question 9
c) Cone 1 will be more depolarized than in question 9
d) Cone 2 will release less glutamate than in question 9

Answer 10

The bipolar cell will be more depolarized than in question 9

Question 11

A stroke can cause blindness restricted to the upper right hemifield if it occurs where?

Answer 11

Left temporal lobe

Question 12

The following statements about cytochrome oxidase blobs are all correct EXCEPT
a) They are centered on ocular dominance columns/stripes
b) A portion of their input comes from layer 4C beta
c) The neurons in blobs are less metabolically active than neurons in the interblob areas d) They appear to play a special role in color perception

Answer 12

The neurons in blobs are less metabolically active than neurons in the interblob areas

Question 13

Blindsight is

Answer 13

The ability to use visual input that is not consciously perceived

Question 14

A visual deficit that involves the loss of motion perception with little or no other deficits is

Answer 14

Akinetopsia

Question 15

In which brain area are there neurons that respond to faces and hands?

Answer 15

Area IT

Question 16

All the following statements about retinotopy are correct EXCEPT
a) The coverage factor in V1 is less than 1
b) Each cone in the retina influences neurons in roughly the same size area in V1
c) Nearby neurons in the LGN project to neighboring areas in V1
d) The totality of the cones in the fovea influence the firing of more V1 neurons than the
totality of cones from an equivalently sized part of the peripheral retina

Answer 16

The coverage factor in V1 is less than 1

Question 17

The elephant shrew is a small mole like creature that has a tiny trunk and,
despite its size, is related to regular gigantic elephants. They communicate with high-pitched 10,000 Hz squeaks. If you fear an encounter with one of these intimidating critters, what aspect of audition would be most useful to localize its 10,000 Hz squeak?

Answer 17

Tonotopy

Question 18

The loudness of the squeaky sound that you perceive is most closely related to which physical measure?

Answer 18

Sound amplitude

Question 19

We’re not sure just how loud the sound of the elephant shrew is, but which of the following is a sound level you might encounter in your daily life that can damage your hearing?

Answer 19

100 dB

Question 20

The ossicle directly connected to the tympanic membrane is the

Answer 20

Malleus

Question 21

All the following statements about the middle ear are correct EXCEPT
a) The amplitude of in and out movements at the eardrum are converted into larger
amplitude in and out movements of the oval window
b) Muscles in the middle ear are responsible for the attenuation reflex
c) The ossicles make the force/pressure at the oval window greater than the
force/pressure at the eardrum
d) It is an air-filled space

Answer 21

The amplitude of in and out movements at the eardrum are converted into larger
amplitude in and out movements of the oval window

Question 22

The stria vascularis

Answer 22

is responsible for the endocochlear potential

Question 23

The organ of Corti sits upon

Answer 23

Basilar membrane

Question 24

The following statements about transduction in auditory hair cells are all correct EXCEPT
a) Calcium entry into the cell body is required for transmitter release
b) Hair cells both depolarize and hyperpolarize in response to sound waves c) Auditory transduction is faster than visual transduction
d) There is a large driving force pushing potassium out of hair cell stereocilia

Answer 24

There is a large driving force pushing potassium out of hair cell stereocilia

Question 25

Which structure in the auditory pathway has the largest proportion of cells responsive to input from only one ear

Answer 25

Cochlear nucleus

Question 26

The principal deficit in Wernicke’s aphasia is

Answer 26

Poor comprehension of speech

Question 27

The most common genetic cause of deafness is a mutation in the GJB2 gene that codes for which protein

Answer 27

Connexin

Question 28

The following points about human sound localization are all correct EXCEPT
a) Is more precise in azimuth than elevation
b) Is based on interaural intensity difference at lower sound frequencies
c) Azimuth localization directly to the front and directly to the back can be confused d) Makes use of sound reflections off the pinna

Answer 28

Is based on interaural intensity difference at lower sound frequencies

Question 29

You are hired to write, “A User’s Guide to the Brain” which gives step by step instructions on how to execute the most basic behaviors. How would you instruct a brain to discriminate fine tactile details like counting the number of small dots on a Braille document?

Answer 29

Touch the document on glabrous skin and analyze the response of Meissner’s
corpuscles and Merkel’s disks

Question 30

A stimulus vibrating at 100 Hz

Answer 30

Will excite rapidly adapting receptors more effectively than slowly adapting receptors

Question 31

A genetic mutation results in Piezo channels that are 10 times more sensitive to their natural stimuli. Which behavioral effect might this mutation generate?

Answer 31

Increased sensitivity to touch

Question 32

Compared to the skin on your back, the skin on your finger tips
a) Has mechanoreceptors with larger receptive fields
b) Has a larger magnification factor in somatosensory cortex c) Has a higher density of mechanoreceptors
d) More than one of the above are true
e) All of the above are true

Answer 32

More than one of the above are true

Question 33

The fastest conducting axons in the peripheral nervous system

Answer 33

Have axons that innervate muscle spindles

Question 34

Damage to the medial lemniscus on the right side of the pons would result in loss of

Answer 34

Touch in the left hand

Question 35

Your roommate runs back from Organic Chemistry lab very excited because they synthesized a new drug that selectively inhibits neurons with cell bodies in the substantia gelatinosa in the dorsal horns of the spinal cord. Ingestion of this drug would cause which effect?

Answer 35

Loss of pain sensation in the body

Question 36

Mirror visual feedback (MVF) from therapy with a mirror box is thought to relieve phantom limb sensations by

Answer 36

Providing visual feedback to the brain that the limb is moving normally which replaces
the feedback from proprioceptors which is now lost in the missing limb

Question 37

Which of the following manipulations would decrease the perception of pain?
a) Injection of morphine into the dorsal horn of the spinal cord
b) Blocking action potentials in axons travelling in the anterior lateral part of the spinal
cord
c) Stimulating the periaqueductal grey matter of the midbrain
d) All of the above

Answer 37

All of the above

Question 38

Peter is bored and wants to create referred pain whereby you feel pain in your hand when you have a stomachache (pain in stomach). Which manipulation would result in this pattern of referred pain?

Answer 38

Causing nociceptors in the stomach to synapse onto neurons in the substantia
gelatinosa that receive input from the hand

Question 39

All of the following are true of the Nav1.7 channels EXCEPT
a) They are found in the membrane of nociceptors
b) They are permeable to sodium
c) Overexpression of the gene coding for these channels can lead to increased sensitivity
to pain
d) Capsaicin, the active ingredient in hot peppers, can directly bind to and activate them

Answer 39

Capsaicin, the active ingredient in hot peppers, can directly bind to and activate them

Question 40

When your brain wants to flex your arm (bring your hand closer to your face) it must
a) Send more action potentials to alpha motor neurons innervating your biceps muscle
b) Send fewer action potentials to neurons innervating your triceps muscle
c) Send more action potentials to gamma motor neurons innervating your biceps muscle
d) All of the above

Answer 40

All of the above

Question 41

Compared to fast-twitch muscle fibers, slow-twitch muscle fibers

Answer 41

Maintain force for a longer time

Question 42

Two muscles have the same number of muscle fibers and they are all fast-twitch. Muscle A has 100 neurons in its motor neuron pool while muscle B has 500 neurons in its motor neuron pool. Which statement is true
a) Muscle A generates more force
b) Muscle B generates more force
c) Muscle A is capable of finer control of level of force
d) Muscle B is capable of finer control of level of force

Answer 42

Muscle B is capable of finer control of level of force

Question 43

Which factor is responsible for determining whether a muscle cells is fast or slow twitch?

Answer 43

The properties of the alpha motor neuron forming a synapse with it

Question 44

Which of the following neurons directly synapse onto alpha motor neurons in the spinal cord?
a) Axons from muscle spindle sensory neurons
b) Axons from interneurons in the same segment of spinal cord
c) Axons from motor neurons in M1 of cortex
d) All of the above

Answer 44

All of the above

Question 45

The cerebellum is attached to your brainstem by the cerebellar peduncles. If Peter were to stop all activity in the cerebellar peduncles this would lead to

Answer 45

Ataxia

Question 46

Stimulating the subthalamic nucleus of the basal ganglia on one side of the brain would likely cause

Answer 46

Decrease in movement in half the body

Question 47

Paresthesia is induced when your foot “falls asleep” (i.e. Blood flow is cut off to your leg and then returning blood flow triggers an immediate strange set of affects.) Paresthesia is associated with all of the following EXCEPT
a) Weakness in leg muscles when you try to stand on the affected leg
b) a “pins and needles” or “foot in a beehive” sensation in the affected foot
c) weak sensory stimuli produce larger than normal sensory responses in the affected foot
d) stronger sensory stimuli are required in the affected foot to elicit a sensation

Answer 47

Stronger sensory stimuli are required in the affected foot to elicit a sensation

Question 48

Stepping on a thumbtack with your left foot would cause all of the following EXCEPT
a) Relaxation of extensor muscles in your right leg
b) Contraction of flexor muscles in your left leg
c) Shifting of your upper body to lean to the right d) Relaxation of flexor muscles in your right leg

Answer 48

Relaxation of extensor muscles in your right leg

Question 49

All of the following are true of Parkinson’s disease EXCEPT
a) It is characterized by excessive dopamine in the striatum (caudate and putamen)
b) Resting tremor
c) Difficulty initiating voluntary movements
d) It can be treated through administration of supplemental dopamine (L-dopa)

Answer 49

It is characterized by excessive dopamine in the striatum (caudate and putamen)

Question 50

Peter being Peter, he injects local anesthetic into the left half of your thoracic spinal cord at T7. While the anesthetic is functioning, you would experience all of the following deficits EXCEPT
a) Loss of movement in your left foot
b) Loss of touch in your left foot
c) Loss of sensation to pain in your right foot
d) Loss of knee jerk reflex in your left leg

Answer 50

Loss of knee-jerk reflex in your left leg