Modulation of movement by basal ganglia and cerebellum Flashcards
what does cerebellum (Cb) and basal gangli (B.G.) do?
modulate activity of UMN
the effects of the Cb and B.G are similar or opposite?
opposite
what sends information to the BG and Cb?
motor cortex
how does Cb and BG send information back to the motor cortex?
through the thalamus
what does the contribution of both systems allow for?
smooth, coordinated movement
what does a disturbance in BG or Cb result in?
motor disorders
what does the BG or nasal nuclei recieve input from?
corticles
what are the 5 parts of the BG?
caudate nucleus & putamen (aka striatum)
Globus pallidus
Substantia nigra
Subthalamic nucleus
thalamus
which is the direct and indirect pathway of the BG
what is disinhibition?
inhibition of inhibition
two inhibitory neurons in a series
what does a reduction of inhibition in the GB lead to?
increase in feedback from the thalamus to the cortex
which BG pathway increases and decreases thalamic excitation of the cortex?
direct - increases
indirect - decreases
is the thalamic output always inhibitory or excitatory
excitatory
Pathway of neurotransmitter of basal ganglia
- cortex -> stiatum : glutamate
- striatum -> globus pallidus : GABA
- globus pallidus -> thalamus : GABA
- subthalamic nucleus -> globus pallidus : glutamate
- thalamus -> cortex : glutamate
which is excitatory and which is inhibitory - glutamate and GABA?
excitatory - glutamate
inhibitory - GABA
what has the highest levels of ACh in the brain?
striatum
where is dopamine produced and released?
produced - substantia nigra
released - striatum
when is dopamine excitatory and when is it inhibitory?
excitatory - direct pathway, D1 receptors
inhibitory - indirect pathway, D2 receptors
what is the overall effect of dopamine on thalamic input to the cortex?
increased input
when is acetylcholine excitatory and when is it inhibitory?
excitatory - indirect pathway
inhibitory - direct pathway
what is the overall effect of acetylcholine on thalamic input to the cortex?
decreased thalamic input to cortex
what does hypoactivation of the basal nuceli circuit cause?
hyperkineasia - inc in movement
what does hyperactivation of basal nuceli circuit cause?
hypokinesia - dec in movement
How is knapweed poisonious to horses?
DDMP inhibits dopamine transport in equine brain
which cranial nerves are most affected by yellow star thistle?
V, VII, IX
what does russian knapweed intoxication do to the facial muscles?
hypertonicity
what does the cerebellum do?
compares intended movement to actual movement and makes adjustement
what do cerebellar lesions result in?
ataxia - uncoordinated muscle movement, don’t prevent movement or impair strength
what are the 3 distinct regions of the cerebellum?
-vestibulocerebellum
-spinocerebellum
-cerebrocerebellum
what allows unconscious control of fine motor movements?
cerebellum
what is the main output of the cerebellum?
motor cortex
what part of the cerebellum regulates balance and eye movements?
vestibulocerebellum
what part of the cerebellum enhances muscle tones and coordinates skilled voluntary movement of different muscle group, and predicts position of body in space during movement?
spinocerebellum
what part of the cerebellum plans and initiates voluntary activity, and stores procedural memory?
cerebrocerebellum
match each cerebellum region with its inputs
inputs - cortex, vestibular system, muscle spindles
regions - vestibulocerebellum, spinocerebellum, cerebrocerebellum
cortex - cerebrocerebellum
vestibular system - vestibulocerebellum
muscle spindles - spinocerebellum
what are the layers of the cerebellum?
molecular layer
purkinje cell layer
granule cell layer
white matter
what is the only output of the cerebellum?
purkinje cells
what are the inputs to the Cb?
-copy of motor plan from cerebral cortex
-sensory information from vestibular system, eyes, skin, joints, muscles
what integrations does the Cb do?
motor and sensory inputs integrated to make an error correction and adjust posture
what is the input of the vestibulocerebellum?
vestibulosensory input from vestibular organ, superior colliculus, striate (visual) cortex
where does the output of the vestibulocerebellum go?
vestibulocerebellum -> lateral & medial vestibular nuclei -> vestibulospinal & bulbar tracts
what are the functions of the vestibulocerebellum?
coordinate movement of head and eyes
control antigravity muscles
what happens if the vestibulocerebellum is damaged?
ataxia, poor balance, wide gate
what is the input of the spinocerebellum?
spinal and trigeminal sensory inputs auditory inputs, striate (visual) cortex
where does the output of the spinocerebellum go?
spinocerebellum -> interposed and fastigal nuclei -> descending brainstem and corticospinal pathways
what is the function of the spinocerebellum?
proper execution of coordinated movement
what happens if the spinocerebellum is damaged?
dysmetria, functional tremor, decreased muscle tone
what is the input of the cerebrocerebellum?
premotor, supplementary and primary motor cortex
where does the output from the cerebrocerebellum go?
cerebrocerebellum -> denate nucleus -> red nucleus -> ipsilateral olivary nucleus -> motor and premotor corticles
what is the function of the cerebrocerebellum?
planning, initiation, timing
learning of motor skills
properly timed movement sequences
what symptoms are seen in patients with cerebellar lesions?
wide gate, ataxia, dysmetria, asynergia, intention tremor, nystagmus, head bobbing
what does canine multiple system degeneration do to the neurological processes?
damages Cb and BG
ataxia -> akinesia and severe posture instability
why would a Cb lesion prior to the decussation cause an ipsilateral motor deficit?
Cb crosses over twice so the area that it would be affecting is the same side as where the lesion is
lesion = no fine tuning of movements = motor deficit
where does the superior cerebellar peduncle cross?
caudal midbrain level
what is canine multiple system degeneration?
fatal familial movement disorder in dogs
what does BVD do to the cows brain?
cerebellar hypoplasia
degenerative purkinje cells and loss of granule cell layer -> reduced cerebellum
what happens to the cerebellum in kittens with panleukopenia virus?
virus attacks rapidly dividing cells in outer layers of cerebellum -> intentional tremor, ataxia, wide gate, head bobbing
