Lecture 3 - Cerebellum

Question 1

What is the cerebellum and what does it do?

Answer 1

-determines whether or not the movement we are performing is correct by incorporating information from the vestibular system about balance and the spinal system about posture and where you are in space

Question 2

What are the spins?

Answer 2

neurological phenomenon when you cannot figure out where your body is in space while you are rotating

Question 3

What does the cerebellum also potentially play a role in?

Answer 3

language processes since it is enlarged in humans and in dolphins which communicate via echolocation

Question 4

What are the three cerebellar peduncles?

Answer 4

superior, middle, inferior

Question 5

What are the three deep nuclei of the cerebellum?

Answer 5

fastigial, interposed, and dentate

Question 6

What do cerebellar purkinje cells have?

Answer 6

great arborization and alot of dendritic branching

Question 7

Why is the cerebellum caudal to the brainstem?

Answer 7

many of the vestibular or motor nuclei that project from the brainstem to the cerebellum are found there

Question 8

How many hemispheres does the cerebellum have and what is it separated by?

Answer 8

-two hemispheres
-separated by the vermis

Question 9

What is the job of the cerebellar peduncles?

Answer 9

-the physical connection between the cerebellum and the brain stem and are -the major connection pathways between the cerebellum and the rest of the brain

Question 10

How many cell layers does the cerebellum have?

Answer 10

three cell layers

Question 11

How many functional divisions or lobes exist for the cerebellum and what is their overall role?

Answer 11

there are three lobes; two send output from the cerebellum and receive input from their corresponding lobe or division

Question 12

What is the name of the lateral lobes of the cerebellum and what is its role?

Answer 12

cerebrocerebellum; implicated in language verb choice, reasoning such as quantitative and spatial; motor planning and executing higher functions

Question 13

What is the name of the medial lobe or vermis and what is its role?

Answer 13

spinocerebellum; key in posture and proprioception and coordinates movement so you can stay upright and have movements and has a body map

Question 14

What is the name of the lobe found at the flocculonodular lobe?

Answer 14

vestibulocerebellum and is the balance hub of the cerebellum; receives afferent and efferent projections from vestibular nuclei in the brainstem

Question 15

What lobe and division sends input to the dentate nucleus and what is the dentate nucleus role?

Answer 15

-the lateral lobes or the cerebrocerebellum
-responsible for motor feedback to execute motor commands that may be implicated in higher order functions like language and verb usage
-largest of the three nuclei
-efferent fibers that leave this nucleus modulate motor function, visuospatial function and conscious thought

Question 16

What lobe or division sends input to the interposed nucleus and what is the interposed nucleus role?

Answer 16

-the vermis or spinocerebellum
-implicated in posture and proproprioception and coordination of movement
-has two divisions: the globose and emoliform nucleus

Question 17

What lobe or division sends input to the fastigial nucleus and what is the role of the fastigial nucleus ?

Answer 17

-the vestibulocerebellum or the flocculonodular lobe
-implicated in balance

Question 18

How many different cell types are in the three layers of the cerebellum?

Answer 18

five different cell types

Question 19

What are the three layers of the cerebellum from outer to inner?

Answer 19

-molecular layer
-purkinje layer
-granular layer

Question 20

What are the two cell types in the molecular layer and are they inhibitory, excitatory, or modulatory?

Answer 20

-stellate cells (like astrocytes)
-basket cells (form synapses)
-inhibitory

Question 21

What cell types are present in the purkinje layer and are they inhibitory, excitatory, or modulatory?

Answer 21

purkinje cells
inhibitory - GABAergic
are the output of the cerebellum since all cellular input converges onto purkinje cells which synapse onto deep nuclei which are the output of the cerebellum

Question 22

What cell types are present in the granule layer and are they inhibitory, excitatory, or modulatory?

Answer 22

-golgi cells - inhibitory - round in shape
-granule cells (most abundant cell type in the CNS) - excitatory

Question 23

What are the two types of fibers present in the cerebellum?

Answer 23

-climbing fibers
-mossy fibers

Question 24

What are climbing fibers?

Answer 24

-fire complex spikes
-originate in the inferior olive of the medulla
-enter the cerebellum via the inferior peduncle to synapse onto neurons in the deep nuclei as well as purkinje cells

Question 25

What are mossy fibers?

Answer 25

-fire simple spikes
-originate in brainstem nuclei and enter the cerebellum via the middle and inferior peduncles and synapse onto granule cells which are excitatory
-outnumber climbing fibers

Question 26

What is a parallel fiber?

Answer 26

axons which extend from granule cells and synapse onto purkinje cells or deep nuclei

Question 27

From what cells can a purkinje cell receive input from?

Answer 27

basket cell/stellate cells, climbing fiber, mossyfiber—>granule cells–>parallel fibers,

Question 28

What kind of spikes do climbing fibers fire versus mossy fibers?

Answer 28

-climbing fibers - complex spikes (since it wraps around multiple times the purkinje cell; repetitive depolarizations before hyperpolarizing)
-mossy fibers - simple spikes

Question 29

What is the motor error feedback loop and what role does the cerebellum play in it?

Answer 29

-the cerebellum detects a difference between the actual movement and the movement and generates an error term and generates then it will try to minimize the error term with the feedback loop provided while the movement is being performed

Question 30

What is the proposed mechanism for learning in the cerebellum by Marr and Albus?

Answer 30

LTD or long terms depression due to gabaergic neurons in the cerebellum; cerebellum will prune away the neurons it does not need making the neurons it does need stronger in comparison

Question 31

What is the VOR?

Answer 31

-the vestibulo-ocular reflex
-an eye reflex that the cerebellum plays an important role in and it is activated when the body is spinning and causes the intraocular muscles to contract in order to cause counteractive eye movements to stabilize the visual field by causing inhibition of one set of extraocular muscles and exciting the other set of extraocular muscles on the other side

Question 32

What are saccades?

Answer 32

the counteractive eye movements that are made to stabilize the visual field when spinning