T2 L5 Cerebellum & motor learning Flashcards
What is the role of the cerebellum?
Maintenance of balance & posture
Coordination of voluntary movements
Motor learning
Cognitive functions
Describe the location of the cerebellum
Inferior to occipital & temporal lobes
What forms the cerebellar cortex?
Grey matter
What are the 3 lobes of the cerebellum?
Anterior
Posterior
Flocculondular
What are the 3 subdivisions of the cerebellum?
Vestibulocerebellum
Spinocerebellum
Cerebrocerebellum
What are the cerebellar nuclei?
Dentate
Fastigial
Interposed
What is the dentate nucleus output?
Areas 4 & 6
Motor planning
What is the fastigial nucleus output?
Medial descending system
Motor execution
What is the interposed nucleus output?
Lateral descending system
Motor execution
What is dysmetria?
Movement is not stopped in time (overshoot)
What is dysnergia?
Decomposition of complex movements
What is dysdiadochokinesia?
Reduced ability trying to perform rapidly alternating movements
What is an intentional tremor?
Arises when trying to perform a goal-directed movement
What is dysarthria?
Articulation incoordination. Incoordination in respiratory muscles, muscles of the larynx etc
What is nystagmus?
Involuntary, rhythmical repeated oscillations of one or both eyes in any or all directions of view
What can cause nystagmus?
Vestibular ocular pathway lesion
What effect can a lesion in spinocerebellar have?
Gait ataxia
Disturbance of limb tone (hypotonia) & posture
What effects can a lesion to cerebrocerebellum pathway cause?
Dysmetria Dysnergia Dysdiadochokinesia Intentional tremor Dysarthria
What is gait ataxia?
Unsteadiness of walking
Where do mossy fibres come from?
Spinal cord
Brainstem
Where do climbing fibres come from?
Inferior olivary nucleus
Where do the deep cerebellar nuclei output to?
Thalami
Vestibular nuclei
Red nucleus
Describe the link with climbing fibres and purkinje cells
One climbing fibre to each purkinje cell with many synapses
Describe the link with parallel fibres and purkinje cells
Many parallel fibres to each purkinje cell with one or few synapses
What do the motor cortex & red nucleus generate signals via?
Corticopontinecerebellar tract
What is proprioceptive feedback from muscles & joints via?
Spinocerebellum & vestibulocerebellum pathways
What is the actual response compared with?
The desired response via cerebrocerebellum inputs from supplementary motor cortex & primary motor cortex to produce error signals
Describe the feedback loop
Error signal is difference between desired input and output
Feedback comes from output
Describe the feedforward loop
Movements that are too fast to be corrected by feedback are executed using predictions of their outcomes based on experience
Advance information used to generate desired output & this fed forward to generate output
What are error signals mainly derived from?
Sensory information
What are error signals sent via?
Inferior olivary nucleus which then lead onto climbing fibres
What are the genetic causes of cerebellar dysfunction?
Friederich’s ataxia
Spinocerebellar degeneration
Ataxia-telengiectasia
Von Hippel Lindau
What are some acquired causes of symmetrical ataxia?
Alcohol Metabolic - B12, thyroid, coeliac Drugs - phenytoin Degenerative - familial, MSA Immune - paraneoplastic
What arteries supply the cerebellum?
Superior cerebellar artery
Anterior inferior cerebellar artery
Posterior inferior cerebellar artery
Why is ataxia less profound if the cerebellar cortex is involved?
It has some degree of plasticity
