Flashcards in Cerebellar function Deck (94):
What are the functions of the cerebellum? (4)
a. coordination of motor acts, planning sequential movements
b. regulation of posture
c. control of muscle tone
d. motor learning
How does the cerebellum accomplish motor function?
Compensates for errors by comparing intention with performance
How does the cerebellum 'know" intentions?
Since information about planes for movement sent to the cerebellum from the cortex
What are the three cerebellar lobes?
What is the function of the flocculonodular lobe?
Works with the vestibular system in controlling equilibrium
What is the longitudinal division of the anterior and posterior lobes?
What are the two parts of the cerebellar hemispheres?
The cerebellar hemispheres and the deep cerebellar nuclei are involved in the control of movement of the ipsilateral or contralateral parts of the body?
What are the two feedback tracts to the cerebellum?
The high fidelity tracts carry what information to the cerebellum?
What is the role of the internal feedback tracts to the cerebellum?
Monitor activity of spinal interneurons and of descending motor signals from the cerebral cortex and brainstem
What is the role of the cerebellum in the cognitive part of speech?
What are the cerebellar nuclei from medial to lateral?
What are the three functional divisions of the cerebellum?
What are the three major inputs into the cerebellum?
1. Mossy fibers
2. Climbing fibers
3. Non-laminar afferents
Where do the mossy fibers come from?
Neurons in the spinal cord and brainstem
Where do the climbing fibers come from?
What are the cells in the cerebellum that contact the climbing fibers?
What are the five main types of cells in the cerebellum?
What is the only cell to project out of the cerebellar cortex?
What is the function of the granule cells in the cerebellum?
What is the function of the golgi cell in the cerebellum?
affect dendritic input to Purkinje cells by inhibiting granule cells
What is the function of the stellate cells in the cerebellum?
affect dendritic integration of Purkinje cells through inhibitory synapses onto dendritic tree
What is the function of the basket cells in the cerebellum?
makes inhibitory synapses near initial segment of Purkinje cell axon
True or false: one action potential in climbing fiber is enough to cause complex calcium-dependent spike in Purkinje cell
What is the relative magnitude of the mossy fiber action potentials compared to ascending fibers? How do they augment this?
Much smaller--spatial and temporal summation
What is the function o the climbing fibers?
changes in the Purkinje cell’s future responses to mossy fiber input and this interaction is believed to be responsible for motor learning
What is the tract from the cortex to the cerebellum?
What is the tract from the cerebellum to the cortex?
What is the route of info from the cortex to the cerebellum?
Is the corticopontocerebellar tract ipsilateral or contralateral?
What is the only cell to project out of the cerebellar cortex?
The mossy fibers come up from the spinal cord and synapse on what cell? Where do these cells synapse?
Granule cells to the purkinje cells
What are the only excitatory cells in the cerebellum?
The parallel fibers are from what cell?
How many climbing fibers does each purkinje cell receive?
Where do almost all of the purkinje cell axons terminate?
Deep cerebellar nucleus
Some to vestibular nuclei
What is the function of the climbing fiber on the purkinje cell?
Input from outside the cerebellum is stimulatory or inhibitory?
Purkinje cells are always inhibitory or excitatory?
Output of deep cerebellar nuclei is usually excitatory or inhibitiory
What is the result of the cerebellar activity?
motor activity first excites deep cerebellar nuclei directly, then after short delay nuclei INHIBITED by Purkinje cells.
What is the anatomical region of the vestibulocerebellum?
What are the inputs to the vestibulocerebellum?
Primary afferents from the vestibular labyrinth/nuclei
What is the output of the vestibulocerebellum?
Purkinje cells projects mainly to the vestibular nuclei and also to the fastigial nucleus
What are thee four functions of the vestibulocerebellum?
How is gait/posture affected by output from the cerebellum?
through vestibulospinal reflexes
True or false: Clinically it can be difficult to distinguish between injury to the vestibulocerebellum or to the peripheral vestibular
apparatus, vestibular nerves or vestibular nuclei
Lesions to vestibulocerebellum can cause what symptoms?
ataxic gait and various
eye movement disorders
What is the anatomical region of the cerebrocerebellum (pontocerebellum)?
Lateral part of the cerebral hemisphere
What is the input to the cerebrocerebellum?
Cortical afferents via pontine nuclei
What is the output of the cerebrocerebellum?
via dentate nucleus to red nucleus and the thalamus which projects to the premotor and primary motor cortex and prefrontal cortex
What is the function of the cerebrocerebellum? (2)
• planning role especially important for multi-joint movements and those requiring fractionated finger movement.
• timing functions
What are the symptoms of a lesion to the cerebro cerebellar cortex or dentate region? (3)
• delays in initiating and terminating movements
• problems with multi-joint movements
• effect on patient’s ability to judge elapsed time in non-motor tasks
The premotor cortex receives projections from neurons in the dentate nucleus which are preferentially involved in what function?
the generation and/or guidance of movement based on visual cues
What are the nuclei involved in the spinocerebellum? Where do these output to?
Interposed and fastigial
Go to motor cortex and brainstem
Deficits with smooth pursuit can be due to a lesion where?
How do cerebellar lesion pts walk?
What is the anatomical region of the spinocerebellum?
intermediate part of hemisphere
What is the input to the spinocerebellum?
somatosensory information from distal body parts (limbs); Also, input from primary motor and somatic sensory cortex
What is the output from the spinocerebellum?
via interpositus (globose and emboliform in humans) to lateral motor systems; red nucleus and also to motor cortex (via the thalamus)
What is the function of the spinocerebellum?
- regulates distal muscles; concerned with ongoing motor execution and regulation of muscle tone
Lesions of the spinocerebellum are ipsilateral or contralateral?
lesions of the spinocerebellum (in general) cause hypo or hypertonia?
What part of the cerebellum has control over saccades?
Lesions of the vermis interfere with what?
Learning to compensate for experimental weakening of an eye muscle
What is ataxia?
loss of muscular coordination due to errors in the range, rate, force, and direction of movement. Movements are jerky and imprecise
Cerebellar ataxia is a term that is usually used for what?
When there is a lesion to the cerebellum itself--not a tract
What is sensory ataxia?
Loss of sensory input can frick up the cerebellum = ataxia
True or false: • Although patients with cerebellar disease usually exhibit ataxia, not all cases of ataxia are caused by cerebellar problems.
What is dysmetria?
errors in the range and force of movement: this is the cause of past pointing
What is hypermetria? Hypometria?
voluntary muscular movement over reaches the intended goal, over shoot target.
Hypometria is when subject undershoots target.
What causes dysdiadochokinesia?
probably caused by abnormal agonist – antagonist control
When dysarthria is caused by cerebellar damage, what is it called?
Static/resting tremor = what damage? Intention tremor?
Static = basal ganglia
Intention = cerebellum
When is a static tremor seen (what does the pt have to do)?
When a pt is holding limb up against gravity
What is titubation? What causes it?
a tremor of the entire trunk or head during stance and gait
Can be caused by midline lesion to the cerebellum
What is cerebellar nystagmus?
nystagmus or oscillatory movements of the eye due to cerebellar-vestibular dysfunction
What is the lobe of the cerebellum that plays a role in balance?
How can the vestibulo ocular reflex be suppressed? When is this impaired?
Impaired in cerebellar lesions
A pendular knee jerk response to a tap on the patellar tendon is a sign of what?
What is synergy? In whom is this problematic?
movements are coordinated over two or more joints to make one smooth movement
What are the limb movements like with asynergia?
errors in the timing of the components of complex multi joint movement. Joints are moved sequentially rather than simultaneously.
What is the rebound phenomenon?
inability of the agonist and antagonist to adapt to rapid changes in load.
The thiamine (vitamin B1) deficiency associated with long term alcoholism can cause atrophy of what?
the anterior lobe of the cerebellum
What are the signs of thiamine deficiency?
Patients can have difficulty walking and with leg control in general, but control of their arms and head is less affected.
True or false: MS pts do not have cerebellar signs
What is Friedreich ataxia?
a recessively inherited progressive spinocerebellar ataxia that is caused by an expanded repetition of the trinucleotide GAA in a gene on chromosome 9.
The premotor cortex receives projections from the cerebellum that are preferentially involved in what?
Movement based on visual cues
Why do some pts with cerebellar deficits show improved motor function when their eyes were closed?
Reduced input to the cerebrum from damaged cerebellum
What is the site of motor learning?
Cerebellum, with the interactions of the climbing fibers and the Purkinje fibers
True or false: the VOR can change
True, if there are not cerebellar lesions
GAA repeat in chr 9 =?