4.19. Cerebellum

Question 1

basic CereBelluM functions

Answer 1

coordination, balance, movement

Question 2

describe how the cerebellum acts as a comparator when receiving input about motor movement

Answer 2

Basically: you make a plan to initiate a movement, then the movement is executed. In this case, there is an error in the execution of the movement, which is registered by the cerebellum. The cerebellum corrects this, then sends the right execution signal back to the brain so you can correct the movement

Question 3

Input to the cerebellum comes mainly from the ___ cortex, and the ___ cortex

areas from which input to the cerebellum comes (hint: its mainly from 2 of the primary something corteces)

Answer 3

Input to the cerebellum comes from the frontal and parietal cortex; mainly the frontal cortex though

Some of the areas from which input comes include basically all the motor areas (precentral gyrus, premotor cortex and supplementary motor areas, somatosensory areas (post central gyrus)), and association areas

Question 4

T/F: information going to the cerebellum from the cortex travels directly to the cerebellum

The input from the cortex to the cerebellum is __ (contralateral/ipsilateral)

Answer 4

Information coming from the cerebral cortex going to the cerebellum passes through the pontine nuclei

The input from the cortex to the cerebellum is contralateral (the fibers cross at the level of the pons - middle cerebellar peduncle - going to the cerebellum)

Question 5

Sensory input to the cerebellum is __ (ipsilateral/contralateral) and mainly comes from the ___and the ___

The sensory information comes through the __ __ __

Answer 5

Sensory input about movement mainly comes from the spinal cord, and the vestibular system (which provides information about head and neck movements). The info comes through the inferior cerebellar peduncle, and is ipsilateral

The inferior olive (receives input from red nucleus) provides mainly contralateral input to the cerebellum that controls the timing of the cerebellum’s function

Question 6

Output from the cerebellum goes through the ___ nuclei

3 main cerebellar nuclei (hint:one of them is actually 2)

Answer 6

Output from the cerebellum goes through the deep cerebellar nuclei

3 main nuclei:

Dentate nucleus – largest one

Interposed nucleus – literally 2 interposed nuclei – emboliform and globose - between the dentate and the fastigial nucleus

Fastigial nucleus – smallest one

Question 7

cerebellar output to the cortex:

From the cerebellar cortex, output goes through the ___ then crosses at the level of the pons (which peduncle?)

From there, it goes up to the ___ and ends there, OR it goes to the ___ thalamus, then back to the primary/premotor cortex areas

Answer 7

From the cerebellar cortex, output goes through the deep cerebellar nuclei (dentate/interposed) then crosses at the level of the pons – superior cerebellar peduncle.

From there, it goes up to the midbrain/tectum/superior colliculus and ends there, OR it goes to the ventrolateral thalamus then back to the primary/premotor cortex areas

Question 8

cerebellar output to brainstem areas

(include the role of the superior colliculus, reticular formation, vestibular nuclei)

info coming thru the superior colliculus can be both ipisilateral and contralateral. how?

Answer 8

From the superior colliculus, info goes to the reticular formation then to the anterior horn of the spinal cord (LMNs) (that’s contralateral if we pass through the SCP and ipsilateral if we go through the ICP)

Question 9

SCP receives input from ___ and part of the spinal cord via the ___ tract

Output from the SCP goes to the __, ___ and ___

Answer 9

inputs from trigeminal, some spinal cord (anterior/ventral spinocerebellar tract, the “double crosser”)

red nucleus, thalamus, reticular formation

Question 10

MCP receives input from the ___ nuclei (hint: the latin name for the MCP is Brachium Pontis)

Answer 10

pontine

Question 11

ICP gets input from the __ and ___; output from ICP goes to the ___, ___ colliculus and ___

Answer 11

Inputs from spinal cord, olivary nucleus

Output to vestibular nuclei, superior colliculus, reticular formation

Question 12

describe what’s happening in the pic (which nuclei are ass’d with which input?)

Answer 12

Question 13

functional subdivisions of cerebellum

Answer 13

vestibulocerebellum - Floccuolonodular lobe: ass’d w/ vestibular functions (balance and eye movements)

spinocerebellum - ass’d with motor control of proximal and distal muscles

cerebrocerebellum - ass’d with higher order motor programming and functions

Question 14

lesions to the cerebellum result in which symptoms?

Answer 14

disrupt coordination of limb movements,

eye movements,

impair balance,

decrease muscle tone,

movement initiation,

spatial control of hand and digit muscles

Question 15

define:

hypotonia

ataxia

(3 kinds of ataxia discussed)

Answer 15

Hypotonia - diminished resistance to passive limb displacements

Ataxia - abnormal execution of voluntary movements

delayed initiation

dysmetria [inaccurate range/direction of movements]

dysdiadochokinesia [irregular pattern of alternating movements]

Question 16

tremor types by cerebellar division

defects are on which side (ipsilateral/contralateral)?

Answer 16

Tremors

Vestibulocerebellum: nystagmus (vestibular - think balance + eye and eye movement/nystagmus is “unbalanced” eye movement)

Spinocerebellum: dyssynergy (think dyssynergy is inaccurate coordination and execution, which is done by spinocerebellum)

Cerebrocerebellum: delayed initiation, dysdiadochokinesia - (this is irregular patterning/think patterning = planning so it’ll be cerebrocerebellum)

dyssynergy:

aspect of ataxia, act is not performed smoothly or accurately because of lack of harmonious association of its various components

dysmetria:

a lack of coordination of movement typified by the undershoot or overshoot of intended position with the hand, arm, leg, or eye

Deficits ipsilateral to the site of cerebellar injury

Question 17

cognitive deficits ass’d w/ cerebellar damage:

which deficits are ass’d w/ the following (what are the brain areas that control these functions?)

executive function

spatial cognition

personality

language

Answer 17

Question 18

3 cell layers in the cerebellum

Answer 18

Molecular layer: most superficial; cell sparse; contains dendrites of the Purkinje cells

Purkinje cell layer: in the middle; send their dendrites into the molecular layer

Granule cell layer: contains tiny cells that look like granules

Question 19

5 cell types in the cerebellar cortex (and the layers they live in)

Afferent fiber types (2 kinds)

T/F: only one of the afferent fibers is glutaminergic

Answer 19

Purkinje cells (inhibitory)
**Granule cells (excitatory)**
Basket cells (inhibitory)
Stellate Cells (inhibitory)
Golgi cells (inhibitory)

Stellate and Basket cells are in the molecular layer

Purkinje cells are in the Purkinje cell layer

Granule cells and Golgi cells are in the granule cell layer

Mossy fibers (excitatory)
Climbing fibers (excitatory)

Falsehood. Both the afferent fibers are glutaminergic

Question 20

How do the golgi, stellate and basket cells deliver their inhibitory outputs?

Answer 20

The golgi cells mainly inhibit the granule cells

The stellate provide GABAergic inhibitory input to the dendrites

The basket cell axons form “baskets” around the cell bodies of Purkinje cells

Question 21

what are the climbing fibers? how do they interact with PCs?

where does input from the Mossy fibers come from? do the fibers interact directly with the PCs? (if not, how do they do this?)

Answer 21

Climbing fibers: axons of the inferior olive; climb up along the dendrites of the Purkinje cells (they only interact with 10 or less PCs)

Mossy fibers: inputs from brainstem and spino-cerebellar tract; send excitatory input to the PC via the granule cells

the granule cells then carry the info to the PCs thru parallel fibers (which run parallel to the surface of the cerebellar cortex)