What is the general functional role of the flocculo-nodular lobe?
- It is involved in vestibular control and vestibular reflexes.
- Thus, it has a role in axial control and balance, eye movement, the vestibuloocular reflex, vestibule-colic reflex and the vestibule-spinal reflex.
general functional role of the vermal and paravermal regions?
The vermal region is involved in axial control, posture, locomotion and gaze reflexes.
The paravermal zone modulates stretch and withdrawal reflexes.
What is the general functional role of the neocerebellum (the large lateral hemispheres)?
The lateral hemisphere regions modulates the brain cortices involved in movement.
types of deficits from cerebellar damage
- always ipsilateral
- cause loss of coordination and equilibrium
- NOT loss of sensation or muscle strength
- HANDS Tremor
H = hypotonia A = ataxia, asynergia N = nystagmus D = dysarthria (slurred speech) S = stance and gait Tremor
lesions of midline vermis impair
coordination of stance and gait, axial trunk posture and equilibrium
Lesions of lateral hemispheres impair the
cerebellar deep nuclei on each side:
- Dentate nucleus
- Globose and emboliform which together make the interposed nucleus
- Fastigial Nuclei
The Dentate nucleus
- has connections from the lateral hemispheric zone.
2. It is involved in planning, initiation and coordination of voluntary movements.
The Interposed nucleus is
- connected to the paravermal zone
2. fine tunes movements of the limbs.
The fastigial nucleus has
- has connections form the vermal zone and is
2. involved in control of axial musculature, posture, balance and integration of head and eye movements.
cerebellar cortex layers
- Lots of parallel fibers (processes of granule cells)
- Dendrites of Purkinje cells
- Stellate and basket cells – inhibitory interneurons
purkinje cell layer
contains cell bodies of purkinje cells
many granule cells, that extend processes superficially to become parallel fibers
There are 2 types of fibers that are the major input tracts to the cerebellum:
- climbing fibers
2. mossy fibers.
Climbing fibers arise from
the contralateral inferior olivary nucleus, ascend in the inferior peduncle.
climbing fibers innervate
innervate all 3 functional zones of the cerebellum (vestibulo-, spino- and cortico-).
mossy fibers arise from
many sources, depending on which zone they are innervating
There are 5 cell types intrinsic to the cerebellar cortex:
- golgi cells
- granule cells
- basket cells
- stellate cells
- purkinje cells
Which cells of the cerebellar cortex have inhibitory actions?
- Purkinje cell outputs on deep cerebellar nuclei are inhibitory, i.e. activity in Purkinje cells turns off the nuclei.
- Basket and stellate cells are inhibitory interneurons
- golgi cells are excited by parallel fibers. They inhibit granule cells
The contralateral inferior olivary nucleus sends information via
climbing fibers, which travel in the inferior cerebellar peduncle to all of the functional zones of the cortex.
Each climbing fiber makes many contacts with a Purkinje cell, so that
each time there is an action potential in the climbing fiber, there will be a lot of depolarization of the Purkinje cell. This functions as an error signal.