exam 3 questions

Question 1

which cells have axons which exit the retina?

Answer 1

ganglion cells

Question 2

which of the following would maximally excite a green ON center, red OFF center surround cell?

Answer 2

shining a green light in the receptive field center

Question 3

what is the difference between ON-center ganglion cells and OFF-center ganglion cells?

Answer 3

ON-center ganglion cells receive their input from ON bipolar cells while OFF-center ganglion cells receive input from OFF bipolar cells

Question 4

what is meant by the term duplex retina?

Answer 4

the retina is capable of both scotopic and photopic vision

Question 5

how many different photopigments are contained in the retina?

Answer 5

four

Question 6

rods are much more sensitive to light than cones because…

Answer 6

rods have a much higher concentration of photopigment

Question 7

in the light, there is a ____ concentration of cGMP in the outer segments of photoreceptors, causing cGMP-gated sodium channels to be in a(n) ____ state.

Answer 7

lower, closed

Question 8

T or F: rhodopsin is a G-protein coupled receptor for light

Answer 8

true

Question 9

the blind spot of the retina

Answer 9

is where the optic nerve exits the retina

Question 10

the center-surround organization of ganglion cell receptive fields is designed to

Answer 10

exaggerate border contrast

Question 11

why do M-type ganglion cells have no color opponency?

Answer 11

M cells receive a mixture of input from more than one type of cone in both center and surround

Question 12

which of the following is FALSE?

• ON-type bipolar cells are sign inverting
• horizontal cells are needed for center-surround receptive fields
• M type ganglion cells have a sustained response to light and small receptive fields
• OFF-type bipolar cells hyperpolarize in light

Answer 12

M type ganglion cells have a sustained response to light and small receptive fields

Question 13

how is color vision best described?

Answer 13

colors are seen by comparing the relative contributors of red, green, and blue cones in response to light

Question 14

if you injected radioactive amino acids into the cell body of a neuron in layer 2 of the left LGN, you would expect to find the label in which layer of striate cortex? (anterograde transport)

Answer 14

layer IVc alpha of the left hemisphere

Question 15

layers 3-6 of your left LGN are destroyed. you would have problems seeing?

Answer 15

fine details of objects in your right visual field

Question 16

which of the following is the major source of synaptic input to the LGN?

Answer 16

striate cortex

Question 17

neurons in primary visual cortex can demonstrate

Answer 17

• direction selectivity
• orientation selectivity
• color opponency

Question 18

the analysis of the shape and orientation is believed to be processed in the

Answer 18

ventral stream

Question 19

which of the following is FALSE:

• magnocellular pathway is used for analysis of motion
• parvo-interblob pathway is mainly used for analysis of color
• nonM-nonP cells contribute to the blob pathway
• parvocellular neurons from LGN synapse in layer IVc beta

Answer 19

parvo-interblob pathway is mainly used for analysis of color

Question 20

T or F: cutting the right optic radiation would cause loss of vision only in left eye

Answer 20

false

Question 21

“ganglion cells that are neighbors in the retina have axon terminals that are neighbors in central visual structures” this organization is an example of

Answer 21

reinotopic mapping

Question 22

which of following is FALSE:

• info from the eye is sent to the hypothalamus, pretectum, and superior colliculus in addition to central visual system
• nonM-nonP ganglion cells synapse in the koniocellular layers of LGN
• most fields in retina, LGN, IVC are circular and respond best to spot of light matched in size to receptive field
• all are true

Answer 22

all are true

Question 23

T or F: cutting the optic chasm would result in visual loss from each hemifield

Answer 23

true

Question 24

T or F: primary sensory afferent axons have widely varying diameters and their size correlates with the type of receptor to which they are attached

Answer 24

true

Question 25

a dermatome is the

Answer 25

area of skin innervated by the dorsal roots of a single spinal segment

Question 26

a roman gladiator is stabbed in the back during the afternoon festivities. the right side of the spinothalamic tract of the SECOND CERVICAL segment is cut. what deficit would result?

Answer 26

loss of nociceptive info from left arm

Question 27

what type of info does the dorsal; column-medial lemniscal pathway carry?

Answer 27

touch and proprioception

Question 28

an individual has lost the ability to feel any sort of pain. using your knowledge of pain perception you propose that this person's lack of pain could stem from?

Answer 28

an unusually high level of activity in the neurons of periaqueductal gray matter

Question 29

you touch the surface of a belgium waffle maker. what is the first thing that will happen in your nervous system?

Answer 29

APs carried by A-beta fibers innervating your hand will reach your CNS

Question 30

cell bodies for peripheral somatosensory afferents are located

Answer 30

within the dorsal root ganglion

Question 31

the sensory homunculus in primary somatosensory cortex

Answer 31

- is an example of somatotopy - reflects the variations in innervation density found in the skin of the body - reflects the amount of use skin gets on different parts of the body

Question 32

referred pain can be explained by neuronal connections within the

Answer 32

spinal cord

Question 33

which of the following is FALSE: - warm receptors signal through C fibers only - hyperalgesia is caused by release of chemicals from damaged cells - naloxone blocks the placebo effect - if your nociceptors are active, you will always feel pain

Answer 33

if your nociceptors are active, you will always feel pain

Question 34

what type of motor neurons ensure that spindle continues to provide info about muscle length during muscle contraction?

Answer 34

gamma motor neurons

Question 35

**the nervous system grades muscles contraction by which of the following mechanisms?

Answer 35

two of the above

Question 36

a motor unit is

Answer 36

one alpha motor neuron and all muscle cells it innervates

Question 37

which of the following is FALSE about red muscle fibers? - fast to contract - fatigue slowly - use aerobic metabolism - present in antigravity muscle

Answer 37

fast to contract

Question 38

what is reciprocal inhibition?

Answer 38

the contraction of one set of muscles is accompanied by the relaxation of the antagonist muscles

Question 39

T or F: each motor unit contains both white and red muscle fibers

Answer 39

false

Question 40

which of the following is false: - AP enters T tubules causing Ca2+ release from SR - Ca2+ binds to troponin, exposing myosin binding sites on actin - gamma motor neurons release ACh to stimulate muscle fibers to contract - myosin binds, head pivots, disengage using energy from ATP

Answer 40

gamma motor neurons release ACh to stimulate muscle fibers to contract

Question 41

which of the following is FALSE: - motor neurons of fast units are larger with faster conducting axons - motor neurons of slow units have smaller diameters, slower conducting axons - alpha motor neurons receive input from spinal interneurons, upper motor neurons and gamma motor neurons

Answer 41

alpha motor neurons receive input from spinal interneurons, upper motor neurons and gamma motor neurons

Question 42

what are central pattern generators?

Answer 42

spinal circuits that give rise to rhythmic motor activity

Question 43

which of the following describes how M1 commands voluntary movement?

Answer 43

the motor cortex is active for every movement, the activity of each cell represents a single vote for a particular direction of movement, and the direction of movement is determined by tally and averaging of the votes registered by each cell in the population

Question 44

which of the following is a symptom of cerebellar damage?

Answer 44

sequential joint movement and dysmetria

Question 45

what is the function of lateral pathways with regard to descending motor pathways?

Answer 45

controls the voluntary movement of detail musculature

Question 46

which of the following is mismatched? - strategy: motor cortex, cerebellum - execution: brain stem, spinal cord - tactics: motor cortex, cerebellum - lateral pathways: inder direct cortical control

Answer 46

strategy: motor cortex, cerebellum

Question 47

consider the motor loop through the basal ganglia. which of the following is the function consequence of cortical activation of the putamen?

Answer 47

excitation of SMA by VL

Question 48

T or F: lesions of the corticospinal tracts cause complete paralysis on the contralateral side

Answer 48

false

Question 49

which of the following is FALSE: - motor map is plastic - neural activity occurs in PMA and SMA neurons before actual movement - prefrontal and pariteal neurons communicate with area 6 - all are true

Answer 49

all are true