Cerebellum Flashcards
Cerebellum function
- Correcting/preventing motor mistakes
- Ensuring accurate and smooth movements
- Associative learning system
- Role in cognition, language
Associative learning system
Learns to associate sensory input from actual movements with intended motor output (match motor output with expected sensory input).
–Contributes to learning new motor skills such as timing and coordination. Contributes to “automatic actions”
Vermis function
Midline movements
- Speech
- Posture
- Stance
- Gait
- Visceral function
Paravermis function
Appendicular movements
- Reaching
- Grasping
Lateral hemisphere function
Extensive reciprocal connections w/cortex
- Spatially and temporally complex movements needing coordination
- Cognition
Internal cerebellum structure
- Cortex
- White matter
- deep cerebellar nuclei
What are the deep cerebellar nuclei?
Dentate Interposed --Emboliform --Globus Fastigial
“Don’t Eat Green Frogs”
What deep cerebellar nuclei is the vermis associated with?
Fastigial
What deep cerebellar nuclei is the paravermis associated with?
Interposed (Emboliform and globus)
What deep cerebellar nuclei are the lateral hemispheres associated with?
Dentate
Cerebellar cortex function
Important for learning new movement combinations
White matter projections
Projections from the cortex to the deep nuclei
Deep cerebellar nuclei
Input: from cortex and direct input
Provide output from cerebellum
Ongoing movement monitoring
Purkinje cell layer
Perpendicular to the parallel fibers. Dendritic cells set up to receive information
How many contacts does each purkinje cell receive from parallel fibers?
10’s of thousands
Where do axons bifurcate from the granule cell layer? What are they called?
Molecular layer.
Parallel fibers
Mossy fibers
Massive in #.
Originate from wide variety of spinal and brainstem locations.
Excite: deep cerebellar nuclei and granule cells in cerebellar cortex.
Multiple mossy fibers synapse on each granule cell
Source of mossy fibers
Spinocerebellum
Vestibulocerebellum
Cerebrocerebellum
Spinocerebellum
Sensory and motor information from spinal cord.
Vestibular, auditory, and visual info
Vestibulocerebellum
Vestibular, auditory, and visual information
Cerebrocerebellum
Cerebral cortex (motor, sensory, prefrontal). Via pontine nuceli (not direct)
Inferior cerebellar peduncle
Ipsilateral input from dorsal and rostral spinocerebellar tracts and cuneocerebellar tract
Middle cerebellar peduncle
Massive contralateral input from pontine nuceli
Superior cerebellar peduncle
Mostly output. Input from ventral spinocerebellar tract
Climbing fibers
Originate in contralateral inferior olive
Where does inferior olive receive input from?
Parvocellular red nucleus, reticular formation, spinal cord
Where do climbing fibers enter the cerebellum from?
Inferior peduncle
Do climbing fibers contact many purkinje cells?
No. Each purkinje cell only gets one climbing fiber
What is the importance of climbing fibers?
Detecting error in motions. Also needed for motor learning.
Reafference
Sensory info from periphery about motions actually occurring. Enables system to identify unexpected conditions
Efference copy (corollary discharge)
Neural copy of motor commands
Spinocerebellar mossy fibers (proprioceptive)
Proprioceptive info (Ia, Ib and II) from ipsilateral muscles through dorsal, cuneocerebellar tract, and mesnencephalic nucleus
Dorsal spinocerebellar tract
C8 and below via Clarke’s column (proprioceptive info)
Cuneocerebellar tract
Rostral to C8 via accessory cuneate nucleus (proprioceptive info)
Mesencephalic nucleus
face (proprioceptive info)
What supplies spinocerebellar mossy fiber motor info?
Ventral spinocerebellar tract and rostral spinocerebellar tract
Ventral spinocerebellar tract
Crosses midline in spinal cord, enters cerebellum through superior CP, crosses again in the cerebellum
Rostral spinocerebellar tract
Starts in cervical spinal cord and stays ipsilateral
Which two tracts have reafference information?
Dorsal spinocerebellar and cuneocerebellar
Which two tracts have efference copy information?
Ventral spinocerebellar and rostral spinocerebellar tracts
Spinocerebellar outputs function
Posture, orientation, gait (vermis) and reaching and grasping (paravermis)
Causes of deficits in spinocerebellum–gait ataxia
Alcohol, some genetic disorders
Spinocerebellar ataxia
Causes gait ataxia. Due to variety of genetic disorders
Alcohol and spinocerebellum deficits
Can be acute or chronic. Chronic abuse leads to deterioration of anterior division from abuse. Wide, staggering gait, little impairment of arms and hands
Deficits in spinocerebellum
Dysmetria Action tremor Timing disorders Movement decomposition Gait ataxia Inability to adapt motor programs to changed circumstances
Vestibulocerebellar outputs
Flocculus and nodulus–> Vestibular nuclei–> Vestibular tracts
Deficits in vestibulocerebellum
Problems with balance and equilibrium (fall toward the side of lesion)
Vertigo
Visual problems (nystagmus, loss of smooth eye pursuit, oscillopsia or diplopia)
Deficits in cerebrocerebellum
Motor control deficits
Impairments in highly skilled motions
Cognitive deficits
Cerebrocerebellum outputs (through parvocellular red nucleus
Lateral cerebellar hemisphere–> dentate nucleus–> parvocellular red nucleus–> inferior olives–> climbing fibers
Cerebrocerebellum outputs (through contralateral VL thalamus)
Lateral cerebellar hemisphere–> dentate nucleus–> contralateral VL thalamus–> cortical motor outputs
