Lecture week 6- The cerebellum Flashcards
Main function of the basal ganglia for motor control
Initiation selection of motor programs - cannot test directly
Main function of the cerebellum for motor control
Motor coordination and correction - can test directly
The 8 motor control parts of the cerebellum
1) maintenance of balance and posture through the vestibular information and proprioception.
2) coordination of multiple muscle groups
3) proprioception input from the muscle spindle and GTO
4) sensory processing
5) adaptability
6) Automaticity: especially to maintain posture
7) motor commands are not initiated in the cerebellum: it modifies motor activity for accuracy
Cerebellums role in motor learning
role in adapting and fine-tuning motor programs to make accurate movement through a trial and error process
Cerebellums role in cognitive functions
not as well studied as its role in motor system however it does seem to be linked to language
the 4 main roles of the cerebellum
1) anticipate the outcome of a motor command in coordination of muscles across several joints
2) Requires proprioception from the muscle spindles
3) Requires vestibular (acceleration, direction, and movement of C spine) for control of balance and equilibrium
4) controls eye reflexed (fixation on target and eye coordination)
The accuracy in time of sensorimotor coordination
- Forward model: able to predict the sensory outcome of movements
- able to correct through error based learning
- Timing, on and off patterns of muscle activation, and direction of movement is critical
What does input to the cerebellum come from?
vestibular receptors and muscle proprioceptors
- allows for adaptations do shifts in body position or changes in muscle loads
what information does the Flocculomodular lobe transport
Vestibular information of equilibrium, balance, and posture
what is the main purpose of the lateral hemisphere of the cerebellum
motor planning and initiating movements for extremities
what is the main purpose of the intermediate hemisphere of the cerebellum
distal limb coordination
what is the main purpose of the vermis and flocculomodular lobe
- Proximal limb and trunk coordination
- Balance and vestibuloocular reflexes
What cells are the major output of the cerebellum
purkinje fibers (inhibitory)
what cells are the major input to the cerebellum
climbing fibers and mossy fibers
(both excitatory)
main cerebellar input pathways (Unconscious input)
- Vestibular input on balance and equilibrium
- Massive motor, sensory, and visual inputs (corticopontine fibers)
Inputs from the periphery lower limbs and trunk
1) dorsal spinocerebellar tract (MS)
2) Ventral spinocerebellar tract (GTO)
ventral spinocerebellar tract
1b from LE (L2 and below)
information for coordinated movement and posture of teh entire lower limb GTO - unconscious perception
Cuneo Spinocerebellar Tract
1a from the UE
Large myelinated axons of primary sensory neurons carry unconscious proprioceptive touch from above C8
Rostral Spinocerebellar Tract
1B from UE
information of coordinated movement and posture of the upper limbs (above c8)
Dorsal spinocerebellar tract
1A from LE and trunk
Large myelinated axons of primary sensory neurons carrying proprioceptive touch, and pressure sensation from the lower extremities and trunk unconscious perception
Inputs from the UE tracts
1) Cuneo spinocerebellar tract (MS)
2) Rostral Spinocerebellar Tract (GTO)
Cerebellum outputs
- no direct connection to the motor system
-output information from the red nucleus to the spinal cord and the VNL of thalamus to the cortex
Major origin of input from the pontocerebellar fibers
cortex
Major origin of input from the dorsal spinocerebellar tract
Leg proprioceptors
major origin of input from the cuneocerebellar tract
arm proprioceptors
Major origin of input from the ventral spinocerebellar tract
leg interneurons
Major origin of input from the rosteral spinocerebllar tract
arm interneurons
main origin of input form the climbing fibers
red nucleus, cortex, brainstem, and spinal cord
main origin of input from the vestibular inputs
vestibular system
how many times does the ventral SC tract cross
twice
how many times does the dorsal, cuneo, and rostral tracts cross
0; they stay unilateral
General deficits in cerebellar function
uncoordinated voluntary movements and problems maintaining balance and posture
Decomposition of movement
unable to produce coordinated, smooth movements because of the loss of the feedforward mechanism
- does not allow for correct timing of the activated muscle sequence, force or awareness
Intension tremor
makes involuntary movement tremor as they approach closer to the target
Romberg and sharpened romberg test
a test to check for cerebellar ataxia (back and forward movement)
PT needs to be standing at the side/behind the patient
patient can have feet together, semitandem or tandem
what to look for in cerebellar exams
speed, coordination, and timing
Dysrhythmia
abnormal timing
Dysmetria
overshoot or past pointing
Dysdiadochokinesia
rapid alternating movements of pronation and supination
Overshooting
holding a testing postion and suddenly letting go
types of cerebellar tests
finger to nose, heel to shin, dysdiachokinesia, tandem walking, Romberg, rapid finger tapping movements
