exam 3 questions Flashcards
which cells have axons which exit the retina?
ganglion cells
which of the following would maximally excite a green ON center, red OFF center surround cell?
shining a green light in the receptive field center
what is the difference between ON-center ganglion cells and OFF-center ganglion cells?
ON-center ganglion cells receive their input from ON bipolar cells while OFF-center ganglion cells receive input from OFF bipolar cells
what is meant by the term duplex retina?
the retina is capable of both scotopic and photopic vision
how many different photopigments are contained in the retina?
four
rods are much more sensitive to light than cones because…
rods have a much higher concentration of photopigment
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.
lower, closed
T or F: rhodopsin is a G-protein coupled receptor for light
true
the blind spot of the retina
is where the optic nerve exits the retina
the center-surround organization of ganglion cell receptive fields is designed to
exaggerate border contrast
why do M-type ganglion cells have no color opponency?
M cells receive a mixture of input from more than one type of cone in both center and surround
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
M type ganglion cells have a sustained response to light and small receptive fields
how is color vision best described?
colors are seen by comparing the relative contributors of red, green, and blue cones in response to light
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)
layer IVc alpha of the left hemisphere
layers 3-6 of your left LGN are destroyed. you would have problems seeing?
fine details of objects in your right visual field
which of the following is the major source of synaptic input to the LGN?
striate cortex
neurons in primary visual cortex can demonstrate
- direction selectivity
- orientation selectivity
- color opponency
the analysis of the shape and orientation is believed to be processed in the
ventral stream
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
parvo-interblob pathway is mainly used for analysis of color
T or F: cutting the right optic radiation would cause loss of vision only in left eye
false
“ganglion cells that are neighbors in the retina have axon terminals that are neighbors in central visual structures” this organization is an example of
reinotopic mapping
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
all are true
T or F: cutting the optic chasm would result in visual loss from each hemifield
true
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
true
a dermatome is the
area of skin innervated by the dorsal roots of a single spinal segment
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?
loss of nociceptive info from left arm
what type of info does the dorsal; column-medial lemniscal pathway carry?
touch and proprioception
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?
an unusually high level of activity in the neurons of periaqueductal gray matter
you touch the surface of a belgium waffle maker. what is the first thing that will happen in your nervous system?
APs carried by A-beta fibers innervating your hand will reach your CNS
cell bodies for peripheral somatosensory afferents are located
within the dorsal root ganglion
the sensory homunculus in primary somatosensory cortex
- 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
referred pain can be explained by neuronal connections within the
spinal cord
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
if your nociceptors are active, you will always feel pain
what type of motor neurons ensure that spindle continues to provide info about muscle length during muscle contraction?
gamma motor neurons
**the nervous system grades muscles contraction by which of the following mechanisms?
two of the above
a motor unit is
one alpha motor neuron and all muscle cells it innervates
which of the following is FALSE about red muscle fibers?
- fast to contract
- fatigue slowly
- use aerobic metabolism
- present in antigravity muscle
fast to contract
what is reciprocal inhibition?
the contraction of one set of muscles is accompanied by the relaxation of the antagonist muscles
T or F: each motor unit contains both white and red muscle fibers
false
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
gamma motor neurons release ACh to stimulate muscle fibers to contract
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
alpha motor neurons receive input from spinal interneurons, upper motor neurons and gamma motor neurons
what are central pattern generators?
spinal circuits that give rise to rhythmic motor activity
which of the following describes how M1 commands voluntary movement?
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
which of the following is a symptom of cerebellar damage?
sequential joint movement and dysmetria
what is the function of lateral pathways with regard to descending motor pathways?
controls the voluntary movement of detail musculature
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
strategy: motor cortex, cerebellum
consider the motor loop through the basal ganglia. which of the following is the function consequence of cortical activation of the putamen?
excitation of SMA by VL
T or F: lesions of the corticospinal tracts cause complete paralysis on the contralateral side
false
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
all are true
