Cerebellum

Question 1

2 ways to divide cerebellum up

Answer 1

one way:
2 hemispheres + vermis

2nd way =
anterior lobe, posterior lobe, floculonodular lobe

Question 2

functional region = vestibulocerebelum
anatomical region?
principal input?
deep nucleus 
principal destination
function

Answer 2

anatomical region = flocculonodular lobe
principal input = vestib sensory cells
deep nucleus  = vestibular
principal destination = axial motor neurons
function = axial control, vestib reflex (balance, eye movement, VOR)

Question 3

functional region = spinocerebellum- vermis
anatomical region = 
principal input = 
deep nucleus 
principal destination
function

Answer 3

anatomical region = vermis
principal input = visual, auditory, vestib, somatosensory
deep nucleus  = fastigial 
principal destination = descending medial systems 
function = axial motor control (posture, locomotion, gaze), integrate head/eye moves, medial/anterior corticospinal

Question 4

functional region = spinocerebellum- paravermal
anatomical region = 
principal input = 
deep nucleus 
principal destination
function

Answer 4

anatomical region = paravermal
principal input = spinal afferents
deep nucleus = interposed
principal destination = contralateral red nucleus, lateral system
function= distal motor control, fine limb movement

Question 5

functional region = cerebrocerebellum
anatomical region = 
principal input = 
deep nucleus 
principal destination
function

Answer 5

anatomical region = lateral hemisphere (beyond paravermal)
principal input = cortical afferents
deep nucleus = dentate
principal destination = integration areas: contralateral VA/VL thalamus --> cortex
function = initiation, planning, movement

Question 6

everything in 3’s in cerebellum

functional division

Answer 6

1) spinocerebellum
2) cerebrocebellum
3) vestibulocerebellum

Question 7

everything in 3’s in cerebellum
3 paired fiber bundles that attach to brainstem
what does each carry

Answer 7

1) inferior cerebellar peduncles = major input to cerebellum
2) middle cerebellar peduncle = major input to cerebellum
3) superior cerebellar peduncles = major output of cerebellum

Question 8

everything in 3’s in cerebellum

cortical layers

Answer 8

1) molec
2) purkinje
3) granule

Question 9

everything in 3’s in cerebellum

architectural features

Answer 9

1) cortex
2) white matter
3) deep nuclei (dentate, interposed, fastigial)

Question 10

efferent connections mostly via ____

efferent output path from vermal cerebellum pathway
exception for flocculonodular lobe

overall function

Answer 10

mostly via deep nuclei

a) from fastigial nucleus, sends efferent info to vestib nucleus and pontine reticular formation

descends in medial descending system via lateral vestibulospinal tract and pontine reticulospinal tract

b) flocculonodular lobe make direct connections with vestib nuclei without fastigial

equilibrium and posture control

Question 11

efferent output path from paravermal cerebellu

Answer 11

1) from interposed nuclei, send efferent through interposed nuclei
2) goes to contralat red nucleus
3) motor output thru rubrospinal tract (lateral descending system)

Question 12

efferent output path from lateral cerebellum

Answer 12

1) info via dentate nucleus
2) goes to contralat ventrolateral thalamus
3) then to primary motor cortex, assoc motor cortex

Question 13

afferent connection into flocculonodular lobe

Answer 13

vestib input

Question 14

afferent input to vermal and paravermal zones

Answer 14

spinal cord input

2 somatotopic distrib arranged head to head with axial body more medial and limbs lateral

input of proprioception (from Clarke’s nucleus) to contralat red nucleus

Question 15

afferent input to lateral zones

Answer 15

no direct!!!

contralateral cortex –> pontine –> lateral zone

contains collateral corticospinal and corticobulbar fibers

Question 16

everything in 3’s in cerebellum

3 effects of lesions

Answer 16

1) synergy
2) equilibrium
3) tone

Question 17

everything in 3’s in cerebellum

3 types of interneurons

Answer 17

1) basket
2) stellat
3) golgi

Question 18

another name for neocerebellum

function

Answer 18

lateral hemispheres

modulates brain cortices involved in movement and planning and init movement

Question 19

what is general functional role of flocculonodular lobe

Answer 19

vestib control and vestib reflexes

axial control, balance, VOR, vestibulo-colic reflex, vestibule-spinal reflex

Question 20

general functional role of vermal region

Answer 20

axial control
posture
locomotion
gaze reflexes

Question 21

general functional role of paravermal region

Answer 21

stretch and withdrawal reflex

Question 22

names of 4 cerebellar deep nuclei on each side

Answer 22

1) dentate
2) globose
3) emboliform
4) fastigial

globose + emboliform = interposed nucleus

Question 23

functions of each of cerebellar deep nuclei

Answer 23

1) dentate = connection from lateral hemisphere for planning, coord of voluntary movement
2) interposed = connection to paravermal and fine tunes movements of limbs
3) fastigial = connections form vermal zone for control axial muscles, posture, balance, integrate head and eye movements

Question 24

types of deficits from cerebellar damage

1) which side of body
2) causes what but not what?
3) what is required for obvious motor effects?

Answer 24

1) always ipsil
2) causes loss of coord and equilibrium but not loss sensation or muscle strength
3) requires damage to deep cerebellar nuclei or large part of cortex

Question 25

types of deficits from cerebellar damage | general classes

Answer 25

1) problems with synergy --> ataxia 2) problems with equilibrium 3) problems with tone

Question 26

types of deficits from cerebellar damage 1) problems with synergy include

Answer 26

ALL D'S 1) dysmetria = can't bring limb to point in space, undershoot or overshoot 2) decomposition of movement 3) dysdiadochokinesia = abnormal, rapid alternating movements

Question 27

lesions of midline vermis cause what? lesions of lateral hemisphere impair what?

Answer 27

impaired coord of stance and gait, axial trunk posture, and equilibrium impair ipsil limb

Question 28

mnemonic for cerbellar lesion effects

Answer 28

HANDS Tremor ``` H= hypotonia A = ataxia, asynergia N = nystagmus D = dysarthria (slurred speech) S = stance and gait ``` Tremor

Question 29

what are cellular components of cerebellar cortex

Answer 29

1) molecular layer = parallel fibers (processes of granule cells), dendrites of purkinjes, stellate and basket inhib interneurons 2) purkinje layer = cell bodies of purkinjes 3) granular layer = many granules (extend processes superficially to become parallel fibers)

Question 30

which cells of cerebellar cortex have inhib action mechanism

Answer 30

stellate and basket parallel fiber --> excite basket/stellate --> inhib of neighboring purkinje cells (lateral inhib) --> disinhib of deep cerebellar neurons--> incr firing

Question 31

2 main fiber tracts to cerebellum

Answer 31

1) climbing | 2) mossy

Question 32

climbing fibers arise from where innerv where

Answer 32

arise from contralat inferior olive nucleus ascend inferior peduncle innervate all 3 functional zones

Question 33

mossy fibers arise from where excite what?

Answer 33

arise from many sources depending on which zone innerv (primary vestib aff/pontine nuclei...) any input not from inferior olivary nucleus = mossy fibers excite granule cells, and each granule contacted by many mossy granule cells then excite Purkinje via parallel fibers

Question 34

describe complex spike vs simple spike

Answer 34

complex spike = due to strong connectionbtwn one climbing fiber and purkinje cell for strong contact (1 AP in climbing = many in purkinje) simple spike = many parallel fiber inputs generate single AP in purkinje

Question 35

4 cell types of cerebellar cortex (golgi, granule, basket, stellate) ramify where purkinje cells have axons that exit where

Answer 35

ramify within cortex exit to cortex to deep nuclei

Question 36

purkinje cell outputs are ____ function? golgi cells excited by ___ for what purpose?

Answer 36

purkinje cell output = inhib to turn off nuclei golgi excited by parallel fibers for feedback inhib of granule cells

Question 37

what inputs to cerebellum are carried by climbing fibers

Answer 37

carry contralat inferior olviary nucleus info in inferior cerebellar peduncle to functional zones of cortex each fiber makes many contact with purkinje cell so each AP in climbing fiber causes lots of depol in Purkinje (error signal)

Question 38

normal operation of cerebellum is what

Answer 38

direct planned motor outputs aligned with expectations (inferior olive) with actual motor performance (spinal afferents in cerebellum as mossy fibers)

Question 39

role of climbing fiber input for motor learning

Answer 39

when inferior olive senses discrepancy btwn planned and actual motor climbing fibers cause complex spike in purkinje mossy fibers activate granule/parallel cause simple spike in purkinje therefore, climbing + mossy depol cause weakening of synapses for movement

Question 40

mossy fibers carry climbing fibers carry

Answer 40

modality specific input that represents copy of reflex input (balance, limb position, eye-hand coordinates) as copy of reflex input from contralateral inferior olivary nucleus for error signals - unexpected responses- reflex activity both for learning

Question 41

everything in 3's in cerebellum | 3 step circuit

Answer 41

1) mossy fibers from diff sources excite granule cell 2) climbing fiber from inf olive nucleus parallel fibers from granule cell converge on purkinje 3) purkinje cell innerv deep cerebellar nuclear cell

Question 42

deep cerebellar nuclei =

Answer 42

cerebellar outputs

Question 43

pathway of climbing fibers pathway of mossy fiber

Answer 43

1) contralat inferior olivary nucleus 2) ascend in inferior cerebellar peduncle 3) innerv all 3 functional zones innerv purkinje cells directly 1) several different zones 2) innerv granule cells

Question 44

Role of climbing fiber input in motor learning

Answer 44

Climbing fiber → complex spike in purkinje fibers granule/parallel cells → simple spike. If both inputs fire at same time, --> learning / plasticity presents itself. In cerebellum, coincidental firinig ==> synaptic modification = LTD ==> subsequent weaker response