Lecture 12, Cerebellum Flashcards
Roles of Cerebellum
key role in regulating movement by regulating functions of motor pathways
compares info about the intention of an upcoming movement by receiving info from motor systems to what actually occurs
Nonmotor functions of Cerebellum
receives info from higher order sensory areas, contributes to language/decision making/affect
Superior cerebellar peduncle
mainly carries outputs from the cerebellum
Middle cerebellar peduncle and inferior cerebellar peduncle
mainly carry inputs
Functional divisons of cerebellum
Vermis
Intermediate part
Lateral part
Vermis
proximal and trunk muscle control, balance, VOR
influences medial longitudinal fasciculus
Intermediate part
control of more distal appendicular muscles in arms and legs
influences LCT and rubrospinal
Lateral part
planning the motor program for the extremities
influences lateral corticospinal tract
Dentate Nucleus
largest of DCN, receive projections from the lateral cerebellar hemispheres
active just before voluntary movements, playing predictive.anticipatory role
Interposed Nuceli
receive input from the intermediate part of the cerebellar hemispheres
active during and in relation to movement
Fastigial Nuclei
input from the vermis and a small amount from flocculonodular lobe. most fibers project to vestibular nuclei and function
Inputs to the cerebellum
mossy fibers
climbing fibers
Mossy fiber inputs
ascend through cerebellar white matter to form excitatory synapses on dendrites of granule cells
granule cells–> send axons into molecular layer, form parallel fibers
parallel fibers fun perpendicular to dendritic trees of purkinje cells
P cells form inhibitory synapses onto the DCN and vestibular nuclei
Climbing fibers inputs
Carry the ERROR message
Wrap around cell body and proximal tree of purkinje cells
strong modulatory effect on purkinje cells, help to decrease the cell response
Output of Cerebellum
axons of purkinje cells into the cerebral white matter
INhibitory cells of cerebellar cortex
basket cells and satellite cells
golgi cells
Deficits in coordination occur _______ to the lesion
ipsilateral
pathways from the cerebellum are double crossed, first in the superior cerebella peduncle
second in corticospinal and rubrospinal
______ lesions in cerebellar vermis effect ______ motor system
Midline
Medial
medial motor systems influence trunk bilaterally
Lateral lesions
affect distal limb corrdination
Medial Lesions
affect trunk control, posture, balance and gait
Lateral cerebellar hemisphere purpose
involved in motor planning
will be carried by purkinje cells to the DCN
projects to dentate nucleus to the superior cerebellar peduncle to reach the VL nucleus of the thalamus to then motor cortex to corticospinal systems
Additional output pathway of lateral hemisphere
some fibers terminate in rostral parvocellular division of red nucelus
projects to inferior olive via central tegmental tract
likely involved in timing of movements
Intermediate Cerebellar Hemisphere outputs
involved in control of ongoing movements of distal extremities
projects to the interposed nuclei, leaves the cerebellum via the superior cerebellar peduncle to contralateral VL thalamus. influences lateral corticospinal tract
also will project to magnocellular division of red nucelus to influence rubrospinal tract
Outputs from Cerebellar Vermis and Flocculonodular Lobe
Begins in vermis, goes to Fastigial Nuceli
carried by superior cerebellar peduncle, crosses and synapse on VL thalamus to influence anterior corticospinal tract and tectal area
also, outputs from fastigial nuclei leave via juztarestiform body to reticular formation and vestibular nuclei (do not cross)
