Cerebellum Flashcards
2 ways to divide cerebellum up
one way:
2 hemispheres + vermis
2nd way =
anterior lobe, posterior lobe, floculonodular lobe
functional region = vestibulocerebelum anatomical region? principal input? deep nucleus principal destination function
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)
functional region = spinocerebellum- vermis anatomical region = principal input = deep nucleus principal destination function
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
functional region = spinocerebellum- paravermal anatomical region = principal input = deep nucleus principal destination function
anatomical region = paravermal
principal input = spinal afferents
deep nucleus = interposed
principal destination = contralateral red nucleus, lateral system
function= distal motor control, fine limb movement
functional region = cerebrocerebellum anatomical region = principal input = deep nucleus principal destination function
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
everything in 3’s in cerebellum
functional division
1) spinocerebellum
2) cerebrocebellum
3) vestibulocerebellum
everything in 3’s in cerebellum
3 paired fiber bundles that attach to brainstem
what does each carry
1) inferior cerebellar peduncles = major input to cerebellum
2) middle cerebellar peduncle = major input to cerebellum
3) superior cerebellar peduncles = major output of cerebellum
everything in 3’s in cerebellum
cortical layers
1) molec
2) purkinje
3) granule
everything in 3’s in cerebellum
architectural features
1) cortex
2) white matter
3) deep nuclei (dentate, interposed, fastigial)
efferent connections mostly via ____
efferent output path from vermal cerebellum pathway
exception for flocculonodular lobe
overall function
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
efferent output path from paravermal cerebellu
1) from interposed nuclei, send efferent through interposed nuclei
2) goes to contralat red nucleus
3) motor output thru rubrospinal tract (lateral descending system)
efferent output path from lateral cerebellum
1) info via dentate nucleus
2) goes to contralat ventrolateral thalamus
3) then to primary motor cortex, assoc motor cortex
afferent connection into flocculonodular lobe
vestib input
afferent input to vermal and paravermal zones
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
afferent input to lateral zones
no direct!!!
contralateral cortex –> pontine –> lateral zone
contains collateral corticospinal and corticobulbar fibers
everything in 3’s in cerebellum
3 effects of lesions
1) synergy
2) equilibrium
3) tone
everything in 3’s in cerebellum
3 types of interneurons
1) basket
2) stellat
3) golgi
another name for neocerebellum
function
lateral hemispheres
modulates brain cortices involved in movement and planning and init movement
what is general functional role of flocculonodular lobe
vestib control and vestib reflexes
axial control, balance, VOR, vestibulo-colic reflex, vestibule-spinal reflex
general functional role of vermal region
axial control
posture
locomotion
gaze reflexes
general functional role of paravermal region
stretch and withdrawal reflex
names of 4 cerebellar deep nuclei on each side
1) dentate
2) globose
3) emboliform
4) fastigial
globose + emboliform = interposed nucleus
functions of each of cerebellar deep nuclei
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
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?
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
types of deficits from cerebellar damage
general classes
1) problems with synergy –> ataxia
2) problems with equilibrium
3) problems with tone
types of deficits from cerebellar damage
1) problems with synergy include
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
lesions of midline vermis cause what?
lesions of lateral hemisphere impair what?
impaired coord of stance and gait, axial trunk posture, and equilibrium
impair ipsil limb
mnemonic for cerbellar lesion effects
HANDS Tremor
H= hypotonia A = ataxia, asynergia N = nystagmus D = dysarthria (slurred speech) S = stance and gait
Tremor
what are cellular components of cerebellar cortex
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)
which cells of cerebellar cortex have inhib action
mechanism
stellate and basket
parallel fiber –> excite basket/stellate –> inhib of neighboring purkinje cells (lateral inhib) –> disinhib of deep cerebellar neurons–> incr firing
2 main fiber tracts to cerebellum
1) climbing
2) mossy
climbing fibers
arise from where
innerv where
arise from contralat inferior olive nucleus
ascend inferior peduncle
innervate all 3 functional zones
mossy fibers
arise from where
excite what?
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
describe complex spike vs simple spike
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
4 cell types of cerebellar cortex (golgi, granule, basket, stellate) ramify where
purkinje cells have axons that exit where
ramify within cortex
exit to cortex to deep nuclei
purkinje cell outputs are ____ function?
golgi cells excited by ___ for what purpose?
purkinje cell output = inhib to turn off nuclei
golgi excited by parallel fibers for feedback inhib of granule cells
what inputs to cerebellum are carried by climbing fibers
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)
normal operation of cerebellum is what
direct planned motor outputs aligned with expectations (inferior olive) with actual motor performance (spinal afferents in cerebellum as mossy fibers)
role of climbing fiber input for motor learning
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
mossy fibers carry
climbing fibers carry
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
everything in 3’s in cerebellum
3 step circuit
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
deep cerebellar nuclei =
cerebellar outputs
pathway of climbing fibers
pathway of mossy fiber
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
Role of climbing fiber input in motor learning
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
