Motor Control 3 Flashcards
what are the 3 lobes of the cerebellum
anterior, posterior, flocculonodular
which lobe is the vestibulocerebellum part of
flocculonodular
what is the function of the flocculonodular lobe
balance and posture
what is the name for the middle part of the cerebellum
vermis (worm)
what are the principle afferents of the cerebellum
pre and primary motor cortex and somatosensory cortex via
pontine nuclei & middle
peduncle
Reticular nuclei
& Olives via inferior
peduncle
Vestibular nuclei via inferior
peduncle
Dorsal (via inferior peduncle) and ventral (via
superior peduncle) ascending spinal
proprioception
what is the function of the flocculonodular lobe
maintains balance and posture
what is the function of the spinocerebellum
modulates axial/ antigravity muscles and eye movement
whatis the function of the cerebrocerebellum
motor planning and feeds information towards the cerebrum
sequence and coordinate distal muscles esp. during locomotion or
juggling etc.
what is the input to the cerebrocerebellum
motor and premotor cortices and somatosensory cortex via multiple pontine nuclei
what is the spinocerebellum input
ascending sensory spinal pathways derived principally from proprioceptors to the spinocerebellum
contains a somatotopical map of the body
what is the input to the vestibulocerebellum
vestibular nuclei
what mnemonic can be used to remember cerebellar output
lat to med
don’t eat greasy food
dentate nucleus
emboliform nucleus
globose nucleus
fastigial nucleus
what is the target of the rostral fastigial nucleus
medial descending systems
(trunk and proximal muscles via reticular formation)
motor execution
what is the target of the interposed nucleus
lateral descending systems
(distal and extremities via spindles)
motor execution
what is the target area of the dentate nucleus
motor and premotor cortices
motor planning function
what is the target of the caudal fastigial nucleus
vestibular nuclei, tectum, cranial nerve nuclei
head and eye movements
how does the cerebellum modulate motor output
integration of activity in pre motor and motor areas plus spinal motor circuits
and sensory feedback from vestibular system, visual system, ascending proprioceptive information
where is modulation by the cerebellum effected
motor cortex and brainstem
where does information from the vestibular apparatus go
passed to the flocculonodular lobe, vermal and paravermal areas
what is the function of the olivary information
enables calculation of predicted posture in advance of it happening, so feed forward posture allows fast postural changes
what is Flocculonodular lobe syndrome
seen in children with medulloblastoma
truncal ataxia, wide based stance and swaying
how does proprioceptive information arrive at the spinocerebellum
via spinocerebellar and cuneocerebellar tracts
where is motor intention information to the spinocerebellum sent from
motor cortex
what movement does the spinocerebellum modulate
truncal and UL and fingers
how does the spinocerebellum work
planned and actual motor output are compared and corrective signals are sent via the thalamus to the cerebra and red nucleus and vestibular nuclei
what is anterior lobe syndrome
errors with the spinocerebellum
overshoot, intention tremous and lack of movement damping
how does information arrive at the cerebrocerebellum
cortex via pontine nuclei
describe the pathway for output from the cerebrocerebellum concerning the order and timing of movements
routed through the dentate nucleus and back via the thalamus to the cortex
what are the functions of the cerebrocerebellum
sequencing and timing of complex movements
also to predict the movement of objects or the movement of oneself in relation to objects
what is the result of medial cerebellar lesions
medial descending pathways affected
unsteady gait; truncal ataxia, problems with balance,
posture and eye movement abnormalities (nystagmus)
how does information arrive at the cerebrocerebellum
cortex via pontine nuclei
why are medial lesions to the vermis bilateral (trunk and proximal muscles)
the medial motor system innervation is bilateral
what is the effect of lateral cerebellar lesions
affect control of distal muscles, motor planning (areas of the cerebellum that control muscles of extremities)
results in limb ataxia
what is the effect of lesions of the cerebrocerebellum
delay in initiation of movement
decomposition of multijoint movements (loss of complex motor skills)
why do unilateral cerebellar lesions give ipsilateral effects
output from the cerebellum is contralateral to the motor centres which then cross back at the pyramids (double cross)
why are medial lesions to the vermis bilateral (trunk and proximal muscles)
the medial motor system innervation is bilateral
what is the effect of lateral cerebellar lesions
affect control of distal muscles, motor planning (areas of the cerebellum that control muscles of extremities)
results in limb ataxia
what is the effect of lesions of the cerebrocerebellum
delay in initiation of movement
decomposition of multijoint movements (loss of complex motor skills)
what is the effect of lesions in the vermis (spinocerebellum)
axial and trunk muscles affected so makes balance unsteady- wide stance
slowed and slurred speech
what is the effect of lesions of the intermediate lobe (spinocerebellum)
distal muscles affected and limb ataxia and action tremour
what are the five subcortical structures of the basal ganglia
caudate nucleus (includes nucleus accumbens) putamen globus pallidus subthalamic nucleus substantia nigra
what is the neostriatum made up of
caudate nuclues and putamen
what is the function of the basal ganglia
refinement and initiation of motor output and the emotial and reward aspects of motor output (limbic loop)
behavioural and learning influence
can initiate movement
what can basal ganglia lesions cause
problems ‘getting going’
what is the collective name for the putamen and the cordate nucleus
neostriatum
describe the accelerator direct pathway
in which the medial GP acts as a brake to movement
cerebral cortex excites the neostriatum with glutamate
neostriatum inhibits the GP medial lobe with GABA
the medial lobe usually inhibits the thalamus
Increased activity at the thalamus results in increased cerebral stimulation and so, increased movement
describe the Indirect pathway ‘The brake’: In which the medial G. Pallidus also acts like a brake
- Cerebral cortex excites the neostriatum with glutamate
- Neostriatum inhibits the Globus Pallidus lateral lobe with GABA
- The lateral lobe normally inhibits the subthalamic nucleus (GABA) but as it is inhibited, the subthalamic
nucleus activity rises - The subthalamic nucleus then increases its normal excitation of the medial lobe of the Globus Pallidus
which increases its activity - Increased activity at medial lobe (brake to movement) results in increased inhibition of the thalamus and
so a reduction in cerebral stimulation . - This in turn results in reduced movement
what are the two parts of the substantia nigra
pars reticularis
pars compacta
what is parkinsons disease
progressive degeneration of the dopaminergic neurones of the substantia nigra
loss of dopamine leads to hypokinesia
how does parkinsons disease cause hypokinesia
a decrease in the direct pathway activity
an increase in the indirect pathway activity
what are the characteristics of parkinsons disease
bradykinesia difficulty initiating movement (akinesia) increased muscle tone tremour of the hands and jaw at rest cognitive impairement
what are the features of huntingtons disease
heritable mutation resuting in malformed protein
loss of encephalinergic and GABAergic neurons in the neostriatum (caudate nucleus)
leading to a decrease in the activity of the indirect pathway
what are the characteristics of huntingtons disease
wildly flailing limbs and contorted posture
reduced ability to saccade (movement of the eye between two fixed points)
abnormal emotional responses
reduced cognitive ability
when does Huntingtons normally occur
50s
life expectancy is 15 years after diagnosis
how is tourettes related to the basal ganglia
believed to be a hyperkinetic disease of the basal ganglia
