Lecture 12: Cerebellum and Motor Control Flashcards
what is the Similarity with cerebrum and cerebellum
Two hemispheres
does the cerebrum or cerebellum have more neurons
cerebellum makes up only 10% of the brain but 4x as many neurons as the cerebrum
how does the cerebellum interact with lower motor neurons
Efferents do not project directly to local circuits or LMNs because it doesn’t initiate movement
how does the cerebellum interact with upper motor neurons
Operates primarily by modifying the activity of UMNs to make movements more accurate
what are the 2 parts of the cerebellum
Cerebellar Cortex
Cerebellar Nuclei
are there different layers of the Cerebellar Cortex
yes
what are the deep nuclei structures responsible for
Output neurons of the cerebellum
how is the cerebellum divided in terms of muscle representation
Axial muscles represented
more centrally
Distal muscles represented more laterally
(sort of somatotopic)
what are the 3 Functional Divisions of the Cerebellum
Vestibulocerebellum
Spinocerebellum
Cerebrocerebellum
what is the function of the Vestibulocerebellum division
Postural Control
what is the function of the Spinocerebellum division
Gross movements of the trunk and limbs
what is the function of the Cerebrocerebellum division
Fine motor voluntary movements
what are Cerebellar peduncles
Connections between cerebellum and other parts of the CNS
what is the closed Cerebro-cerebello-cerebral loop
Output to corticospinal tract double crosses = ipsilateral representation
what are the 3 main functions of the cerebellum
Coordination of multi-jointed movement
Postural control
error correction
how does the cerebellum perform error correction
Integrates executive commands with sensory feedback
how does the cerebrum compare intended and actual movement (4 steps)
initial feedforward blueprint (efference copy)
Cerebellum predict the amount of sensory input
Sensory inputs provide afferent copy/feedback
Cerebellum compares predicted sensory input with actual sensory input to reduce error
do cerebellar lesions cause ipselateral or contralateral leisons
ipsilateral
what are the 3 signs of a cerebellar lesion
ataxia (incoordination)
poor postural control
difficulty learning highly skilled sequences
do we see sensory or strength issues with a cerebellar lesion
no
what 3 things do we see with Vestibulocerebellum damage
Spontaneous nystagmus
Postural instability
Truncal ataxia
what do we see with Spinocerebellum damage
Damage to vermis
* Truncal ataxia
Damage to paravermis
* Limb ataxia
* Ataxic gait
what do we see with Cerebrocerebellar damage
Loss of coordination of fine finger movements
what are the 3 types of limb ataxia
intention tremor
dysmetria
dysdiadochokinesia
what is intention tremor
Tremor during movement
that increases as you reach target
what is Dysmetria
Inability to gauge the distance (overshooting or undershooting)
what is Dysdiadochokinesia
Difficulty performing rapid alternating movements
what is motor control
The ability to regulate or direct the mechanisms essential to movement
Normal motor control relies heavily on which 3 types of information:
visual
somatosensory
vestibular
why are Basal Ganglia and Cerebellum heavily involved in motor control
Feedforward and feedback interact to create and adjust movement
3 main types of upper extremity impairments of motor control
Perceptual problems
Reach and grasp impairments
Grasp and in-hand manipulation impairments
what are perceptual problems with motor control
can be caused by neglect
Difficulty locating target
(visual agnosia)
Difficulty planning and executing reach and grasp
what is the Largest contributor to impaired reaching post- stroke
Loss of individuation/development of abnormal synergies
what is loss of individuation
Obligatory co-activation of muscles during voluntary motion
stronger in antigravity muscles, usually flexors in upper extremity, extensors in lower extremities
what are the 2 potential mechanisms for loss of individuation
Upregulation of extrapyramidal tracts
Cortical reorganization
what are 2 Grasp and In-Hand Manipulation Impairments in motor control
Impaired feedforward control and force scaling
increased reliance on feedback
If damaged, which of the following structures would MOST affect coordination of movement?
Basal ganglia
Cerebellum
Motor cortex
Premotor cortex
Cerebellum
Damage to one side of the cerebellum would result in:
Impaired coordination contralateral to the damage
Impaired strength ipsilateral to the damage
Impaired sensory function ipsilateral to the damage
Impaired coordination ipsilateral to the damage
Impaired coordination ipsilateral to the damage
