Module 2: Cerebellum

Question 1

what do lesions of the cerebellum cause

Answer 1

disruption of coordination of limb and eye movements, impair balance, and alter muscle tone

Question 2

what is the general function of the cerebellum

Answer 2

paying attention to sensory stimuli that help us move more efficiently and to ignore unimportant, unhelpful stimuli

Question 3

what is the hallmark of a normal cerebellum function

Answer 3

cerebellum output decreases

Question 4

vermis

Answer 4

middle region of the cerebellum

Question 5

spinocerebellum

Answer 5

the vermis plus two intermediate areas called the paravermis

Question 6

cerebrocerebellum

Answer 6

two large lateral hemispheres on either side of the paravermis

Question 7

flocculonodular lobe of the vestibulocerebellum

Answer 7

the smallest section of the cerebellum that looks like a bow-tie

Question 8

what kind of information does the cerebellum receive

Answer 8

• somatosensory
• visual
• auditory
• vestibular
• proprioceptive

Question 9

what kind of input does the cerebellum receive

Answer 9

motor cortex, somatic sensory and secondary visual cortices

Question 10

where does the cortical cerebrocerebellar pathway relay and travel through?

Answer 10

relays in pons, goes through middle cerebellar peduncle, provides sensory info about movement

Question 11

where do most cortical inputs synapse and enter the cerebellum

Answer 11

most synapse in the pons and enter via the middle peduncel

Question 12

where do vestibular inputs to the cerebellum enter

Answer 12

through the inferior cerebellar peduncle and project to the vestibulocerebellum

Question 13

what are the spinal inputs to the cerebellum

Answer 13

axons from the dorsal nucleus of Clark in the spinal cord
- receive proprioceptive input from the muscle spindles and project through the inferior cerebellar peduncle to the spinocerebellum

Question 14

what inputs are referred to as mossy fibers

Answer 14

fibers from pons that enter the cerebellum through the middle peduncle + spinal and vestibular afferents entering through inferior peduncle

Question 15

what do the pontine mossies do

Answer 15

relay info from the cerebral cortex

Question 16

what do mossies that go through the inferior peduncle do

Answer 16

send sensory information from medulla, cranial nerve 8, and spinal cord

Question 17

where do all mossy fibers synapse?

Answer 17

granule cells

Question 18

where do granule cells connect

Answer 18

they send parallel fibers to synapse on Purkinje neurons

Question 19

three layers of cerebellum

Answer 19

granule cell layer, purkinje cell layer, molecular layer

Question 20

main function of granule cell layer

Answer 20

sends axons (parallel fibers) to the dendrites of the purkinje cells

Question 21

characteristics of inputs from the inferior olive

Answer 21

they are modulatory and participate in cerebellar learning

Question 22

where do climbing fibers come from

Answer 22

the inferior olive in the medulla

Question 23

where do climbing fibers enter the cerebellum

Answer 23

through the inferior peduncle

Question 24

where do climbing fibers synapse

Answer 24

directly on purkinje cells

Question 25

what kind of information do climbing fibers carry

Answer 25

instructive information

Question 26

characteristics of purkinje neurons

Answer 26

GABAergic, send cerebellar cortical output to the DCN

Question 27

what are the two classes of excitatory inputs that innervate the cerebellar cortex

Answer 27

climbing fibers, and mossy fibers

Question 28

characteristics of mossy fibers

Answer 28

synapse on DCN and on granule cells in cerebellar cortex

Question 29

what are climbing fibers

Answer 29

inputs from inferior olive that synapse directly on Purkinjes

Question 30

what are mossy fibers

Answer 30

sensory inputs and inputs from motor cortex that synapse on granule cell

Question 31

what kind of spikes do climbing fibers display

Answer 31

complex spikes

Question 32

what kind of spikes do parallel fibers display

Answer 32

simple spikes

Question 33

what do mossy and climbing fibers have in common

Answer 33

- both send axon collaterals to the deep cerebellar nuclei and cerebellar cortex - both are excitatory inputs

Question 34

where do Purkinje cells project

Answer 34

deep cerebellar nuclei

Question 35

where does the cerebrocerebellum project

Answer 35

dentate nucleu

Question 36

where does the dentate nucleus project

Answer 36

premotor cortex (motor planning)

Question 37

where does the spinocerebellum project

Answer 37

interposed and fastigial nuclei

Question 38

where do interposed and fastigial nuclei project

Answer 38

motor cortex and brainstem (motor execution)

Question 39

where does the vestibulocerebellum project

Answer 39

vestibular nuclei

Question 40

where do the vestibular nuclei project

Answer 40

lower motor neurons in spinal cord and brainstem (balance and vestibulo-ocular regulation)

Question 41

true or false: each purkinje neuron receives input from many climbing fiber

Answer 41

false

Question 42

true or false: parallel fiber firing elicits complex spikes in the Purkinje neuron

Answer 42

false

Question 43

true or false: a given Purkinje neuron receives either parallel fiber or climbing fiber input but not both

Answer 43

false

Question 44

true or false: the cerebellar cortex contains multiple somatotopic maps

Answer 44

true

Question 45

what is motor learning?

Answer 45

procedural/ trial-and-error learning

Question 46

characteristics of procedural memories

Answer 46

- robust (like learning to ride a bike) - circuits involve simple reflex pathways linking sensory input to a motor output

Question 47

difference between reflex and learning

Answer 47

reflex = trying to stabilize yourself learning = not getting off balance in the first place

Question 48

where does input from the inferior olive enter and what are they called

Answer 48

enter through the inferior peduncle and are called climbing fibers; signal motor error

Question 49

what is classical conditioning

Answer 49

a type of procedurally learned behavior

Question 50

how does classical conditioning involve a reflex

Answer 50

an 'unconditioned stimulus' automatically produces an 'unconditioned response'

Question 51

how does classical conditioning involve learning

Answer 51

associates a new 'conditioned stimulus' with the unconditional stimulus

Question 52

what is the conditioned response

Answer 52

when the conditioned stimulus triggers the response even in the absence of the unconditioned stimulus

Question 53

what is the unconditioned stimulus in Pavlov's dog

Answer 53

meat

Question 54

what is the unconditioned response in Pavlov's dog

Answer 54

salivation

Question 55

what is the conditioned stimulus in Pavlov's dog

Answer 55

tone

Question 56

what is the conditioned response in Pavlov's dog

Answer 56

the modified (learned) behavioral response to the conditioned stimulus after pairing

Question 57

what do complex spikes occur in response to

Answer 57

climbing fiber excitation and signal error

Question 58

what are simple spikes driven by

Answer 58

mossy fiber input and signal sensory stimuli - mediated by AMPA receptors on the Purkinje neuron

Question 59

when is motor performance bad

Answer 59

when a novel task is introduced

Question 60

when does complex spike firing decrease

Answer 60

when learning is complete and there are no motor errors

Question 61

what is motor error

Answer 61

intended motor behavior is different from the actual motor output

Question 62

when are synapses candidates for removal

Answer 62

when sensory information coming in via simple spikes is unhelpful

Question 63

what is the marr-albus theory of motor learning

Answer 63

that the climbing fiber activity signals that a movement has failed to meet a prediction and that corrections are then made by adjusting the effectiveness of the parallel fiber inputs to the Purkinje cell

Question 64

evidence for the role of cerebellum in eyeblink conditioning

Answer 64

- stimulation that activates mossy or climbing fibers can be effective in conditioning - cerebellar lesions disrupt eyeblink conditioning

Question 65

how does the purkinje cell change its response

Answer 65

synaptic plasticity

Question 66

what is long term depression caused by

Answer 66

internalization of the AMPA type glutamate receptor on postsynaptic neurons

Question 67

what happens to AMPA receptors on Purkinje cells during learning

Answer 67

they are internalized at parallel fiber synapses that were active when errors occurred

Question 68

what happens if a parallel fiber is active at the same time as the climbing fiber input to the post-synaptic purkinje neuron

Answer 68

a decrease in its ability to cause a neuron to fire will occur

Question 69

when does synaptic plasticity occur

Answer 69

only when the climbing fibers and parallel fibers co-activate the Purkinje neuron - long term depression occurs

Question 70

what happens when there is an error

Answer 70

the Purkinje neuron is stimulated by both the climbing fiber and parallel fiber - this activates 2nd messenger systems in the cell --> internalization of AMPA receptors

Question 70

what does long term depression at parallel fiber synapses control

Answer 70

time dependent adjustments of the eyeblink reflex

Question 71

what is the decline in simple spikes due to

Answer 71

long term depression

Question 72

what carries the unconditioned stimulus

Answer 72

the climbing fibers - causes complex spike in Purkinje

Question 73

what carries the conditioned stimulus (tone)

Answer 73

the mossy --> parallel fibers (causes simple spikes)