cerebellum

Question 1

describe the function of the cerebellum

Answer 1

• Role is to calculate velocity, duration, force and timing of muscle action to ensure body movements are carried out with precision
• Proprioceptive feedback to maintain balance and upright posture at rest and during locomotion, and integrating eye and head movements
• involved in “procedural memory”, complex motor learning such as riding a bike or playing a piano

Question 2

describe the peduncles connecting cerebellum to brainstem

Answer 2

• Superior peduncle = connects with midbrain (Major OUTPUT)
• Middle peduncle = connects with pons (Major INPUT)
• Inferior peduncle = connects with medulla (Input and output)

Question 3

describe the Flocculonodular lobe/vestibulocerebellum

Answer 3

• FUNCTION: posture, balance, eye/head movements (anti-gravity)
• INPUT = vestibular system (inner ear and nuclei)
• OUTPUT = vestibular nuclei, vestibulospinal tracts, medial longitudinal fasciculus (eye and head movement integration - interconnects III, IV, VI)
• DEEP NUCLEI = primarily directly to vestibular nuclei

Question 4

describe the vermal/paravermal areas (SPINOCEREBELLUM)

Answer 4

• FUNCTION = muscle tone and adjusting movemetns of axial trunk and proximal limbs
• INPUT = dorsal and ventral spinocerebellar tracts, cuneocerebellar, trigeminocerebellar (proprioceptive)
• OUTPUT = vestibulospinal and reticulospinal tracts
• DEEP NUCLEI = fastigial and interposed

Question 5

describe the lateral hemispheres (Cerebrocerebellum)

Answer 5

• FUNCTION = precise control of executed movements (timing, duration, force, velocity, and trajectory of movements)
• INPUT = corticopontocerebellar tracts (motor cortex INTENT) and olivocerebellar tract (timing or procedural learning?)
• OUTPUT = dentorubrothalamic tract (FEEDBACK to motor cortex via VL nuclei of thalamus) and to rubrospinal tracts
• DEEP NUCLEI = dentate

Question 6

What are the cell types in the outer molecular layer of the cerebellum

Answer 6

• synpatic area plus basket and stellate cells

Question 7

describe the cell types in the middle PURKINJE CELL LAYER

Answer 7

• Principle cells in functional significance
• ALWAYS INHIBITORY TO DEEP CEREBELLAR NUCLEI

Question 8

describe the cell types in the INNER GRANULE cell layer

Answer 8

• granule cells and golgi cells

Question 9

describe the climbing fiber system

Answer 9

• olivocerebellar tract (from inferior olive)
• ECITATORY SYNPASES ON PURKINJE CELLS
• ONE TO ONE RELATIONSHIP WITH PURKINJE CELLS

** BOTH MOSSY and climbing fibers send EXCITATOY COLLATERALS to deep nuclei

Question 10

describe the deep cerebellar nuclei output

Answer 10

• deep cerebellar nuclei output is a product of excitatory climbing and mossy fibers and INHIBITORY PURKINJE FIBER activity

Question 11

Describe how cerebellum and basal ganglia are different

Answer 11

BASAL GANGLIA - have a permissive function

–> Inhibiting involuntary movements

–> facilitating voluntary movements

CEREBELLUM - has execution function

–> PLANS MOVEMENTS ordered by motor cortex

–> provides CORRECTIVE FEEDBACK to motor cortex

–> FINE TUNES ongoing movements

Question 12

How are cerebellum and basal ganglia similar?

Answer 12

• both influence motor cortex vita thalamus (VL)
• Both modify or adjust motor commands
• NO PARALYSIS WITH LESION

Question 13

Describe the result of a Lesion of the cerebellum

Answer 13

• typically showIPSILATERAL (SAME SIDE) SIGNS AND SYMPTOMS
• since no cerebellar neurons have DIRECT control of any muscles, THERE IS NO PARALYSIS

Question 14

define inferior olivary nucleus

Answer 14

• Timing mechanisms
• procedural learning
• adaptive learning - signals from iferior olive to purkinje cells (olivocerebellar pathway) reinforces “corrective action” taken by motor cortex (practice makes perfect)

Question 15

describe deep cerebellar nuclei OUTPUT

Answer 15

• Output of the deep cerebellar nuclei is a product of excitatory climbing and mossy fibers and INHIBITORY purkinje fiber activity