Week 6.6

Question 1

What is the role of the cerebellum?

Answer 1

fine-tune reflexes and voluntary movements

Question 2

What are the three parts of the cerebellum?

Answer 2

• cerebrocerebellum
• spinocerebellum
• vestibulocerebellum

Question 3

What are the functions of the cerebrocerebellum, spinocerebellum, and vestibulocerebellum?

Answer 3

• cerebro: initiation and programming of movement
• spino: ongoing correction of movement errors
• vestibule: control of vestibular reflexes

Question 4

Output from the cerebellar cortex is primarily mediated by what cell type?

Answer 4

purkinje cells

Question 5

Describe the output of purkinje cells?

Answer 5

they project to deep cerebellar nuclei and have an inhibitory effect

Question 6

Purkinje cells use what neurotransmitter?

Answer 6

GABA

Question 7

Granule cells form what connections within the cerebellum?

Answer 7

they form parallel fibers and form many excitatory synapses with purkinje cells

Question 8

What are the two inputs of the cerebellum?

Answer 8

climbing fibers and mossy fibers

Question 9

What are cerebellar climbing fibers?

Answer 9

fibers that originate from the inferior olivary nucleus and synapse directly onto purkinje cells

Question 10

What are mossy fibers?

Answer 10

fibers from the pontine nuclei and spinocerebellar tracts the form synapses on granule cells and modify their output onto purkinje cells

Question 11

Cells in the deep cerebellar nuclei project to what structure?

Answer 11

the contralateral thalamus and red nucleus

Question 12

How does climbing fiber input differ from mossy fiber input onto purkinje cells?

Answer 12

climbing fibers lead to an obligatory AP and elicit a complex spiking pattern while mossy fibers elicit a simple and graded response

Question 13

Cerebellar efferents travel to the thalamus via what structure?

Answer 13

the superior cerebellar peduncle

Question 14

Describe the pathway between the motor cortex and cerebellum.

Answer 14

• motor cortex
• pontine nucleus
• middle peduncle
• cerebellar cortex
• deep nuclei
• thalamus
• motor cortex

Question 15

What is the pontine nucleus?

Answer 15

a relay station for information going from the cortex to the cerebellum, letting it know what the intended movement is

Question 16

The cerebellum projects directly to the spinal cord via what midbrain structure?

Answer 16

the red nucleus

Question 17

The output of the vestibulocerebellum primarily goes to what other systems?

Answer 17

• vestibulospinal tract

- reticulospinal tract

Question 18

Why would the vestibulocerebellum want to suppress the VOR?

Answer 18

so that we can tract an object by moving our head

Question 19

If someone has ataxia but is able to perform the Romberg test, it means what?

Answer 19

that the ataxia is not sensory but rather is cerebellar in nature

Question 20

How is a lesion of the vestibulocerebellum likely to present?

Answer 20

with nystagmus and dysequilibrium or wavering, ataxic gait

Question 21

How is a lesion of the cerebrocerebellum likely to present?

Answer 21

• hypotonia
• ataxia
• intention tremor
• dysdiadochokinesis
• decomposition of movement

Question 22

What is dysdiadochokinesis?

Answer 22

the inability to make rapid, alternating movements and a sign of cerebrocerebellar lesion

Question 23

What is decomposition of movement?

Answer 23

comple movements involving multiple joints are not made with continuous smooth trajectories, a sign of cerebrocerebellar lesion

Question 24

Do cerebellar lesions affect contralateral or ipsilateral limbs?

Answer 24

ipsilateral

Question 25

What is the primary function of the basal ganglia?

Answer 25

- to select which movements form the cortex actually get performed - disinhibit CNS structures to allow for the initiation of voluntary movements

Question 26

What is the steady state activity of the basal ganglia?

Answer 26

it has a high tonic inhibitory firing rate that is decreased when it decides to allow a movement

Question 27

Which basal ganglia component is the receiving part?

Answer 27

the striatum

Question 28

What is the output nucleus of the basal ganglia?

Answer 28

the globus pallidus

Question 29

What are the four components of the basal ganglia?

Answer 29

- striatum - globus pallidus - sub thalamic nuclei - substantia nigra

Question 30

Which basal ganglia neurons are dopaminergic?

Answer 30

those in the substantia nigra pars compacta (SNc)

Question 31

Which neurons are targeted by Parkinson's disease?

Answer 31

dopaminergic neurons in the substantia nigra pars compacta

Question 32

How does Parkinson's disease lead to bradykinesia?

Answer 32

- loss of substantia nigra pars compacta input on the putamen - creates an imbalance in the basal ganglia that favors the indirect pathway - the thalamus is inhibited and the cortex can't initiate movement

Question 33

What is hemiballismus?

Answer 33

a movement disorder characterized by high velocity, large amplitude involuntary flinging movements, usually involving the arms

Question 34

What neuron population is targeted by Huntington's chorea?

Answer 34

GABAergic neurons from the putamen to the GPe

Question 35

Hemiballismus is associated with what lesion?

Answer 35

lesions of the sub thalamic nucleus

Question 36

Overactivity of the direct pathway within the basal ganglia will cause what sort of movement disorders?

Answer 36

hyperkinetic disorders