Lecture 13: Modulation for movement by the basal ganglia and cerebellum Flashcards
What two structures modulate activity of the upper motor neurons
Cerebellum and basal ganglia
T or F: cerebellum and basal ganglia generate movement
False!
The ___ sends information to the cerebellum and basal ganglia
Motor cortex
The cerebellum and basal ganglia send information back to the motor cortex through the ___
Thalamus
T or F: the effects of cerebellum and basal ganglia are similar
False, opposite
The contribution of the basal ganglia and the cerebellum allow for ___, ___ movements
Smooth and coordinated movement
Disturbances in either the cerebellum or basal ganglia will create ___ disorders
Motor
What are the 5 parts of the basal ganglia
- Caudate nucleus and putamen
- Globes pallidus
- Substantia Nigra
- Subthalamic nucleus
- Thalamus
What role does the caudate nucleus and putamen play in the basal ganglia
Receives excitatory input from the cortex
What two structures make up the globus pallidus
External/outer segment and internal/inner segment
What two structures make up the substantia nigra
Pars compacta and pars reticularis
What does the thalamus do in the basal ganglia
Sends modulated excitatory feedback to the cortex
describe the direct pathway
1.cortex signals to striatum (putamen)
2. Striatum sends inhibitory signal to globulus pallidus (internal) and substantia nigra (pars reticulata)
3. Those two structures send an inhibitory signal to the thalamus resulting in disinhibition of thalamus
4. Thalamus sends stimulatory signal to cortex to increase activity in cortex
5. Cortex sends out signal to upper motor neurons
Describe the indirect pathway
- Cortex signals to striatum
- Striatum sends inhibitory signals to globulus pallidus which inhibits subthalamic nucleus
- Subthalamic nucleus sends activating signal to globulus pallidus and substantia nigra
- Activated globulus pallidus and substantia nigra will NOT disinhibit thalamus
- Thalamus will decrease activating signal sent back to cortex
What is disinhibition
Inhibition of inhibition
What does disinhibition result in
Reduction in inhibition that leads to an increase in feedback from the thalamus to the cortex
Thalamus output is always___
Excitatory
Direct pathway ___thalamic excitation of the cortex
Increases
The indirect pathway ___ thalamic excitation of the cortex
Decreases
What neurotransmitter does the cortex release onto the striatum
Glutamate
What neurotransmitter does the substantia nigra release onto striatum
Dopamine
Damage to the substantia nigra can cause what kinds of diseases
Parkinsonian
What neutrotransmitter do the striatum interneurons release
Acetylcholine
What neurotransmitter does the striatum release onto the globus pallidus
GABA
What neurotransmitter does the globulus pallidus release onto the thalamus
GABA
What does the Subthalamic nucleus release onto the globulus pallidus
Glutamate
What does the thalamus release onto cortex
Glutamate
Where is dopamine produced in the brain
Substantia nigra
Where is dopamine released in the brain
Striatum/putamen
DA is __ to cells in the striatum as part of the direct pathway
Excitatory
What receptors does DA stimulate in direct pathway
D1
DA is __ to cells in striatum that are part of the indirect pathway
Inhibitory
What receptors does dopamine act on in the indirect pathway
D2
What produces ACh and where
Interneurons in the striatum
ACh is ___ to cells in the striatum that are part of the direct pathway
Inhibitory
The striatum releases ACh onto ___ in the direct pathway
Globulus pallidus and substantia nigra
ACh is ___ to cells in the striatum that are part of the indirect pathway
Excitatory
The effects of ACh are ___ to that of DA
Opposite
Effects of dopamine ___ thalamic input to cortex
Increase
Effects of ACh ___thalamic input to the cortex
Decrease
How do you achieve balance of direct and indirect pathway
Balance ACh and DA in brain
Activation of the direct basal nuclei pathway ___excitation of the cortex
Increases
Activation of the indirect basal nuclei pathway ___ excitation of the cortex
Decreases
Increased ___signaling in both pathways increases excitation of the cortex
Dopamine
Increased ____signaling in both pathways decreased excitation of the cortex
Acetylcholine
Damage to the basal nuclei results in two kinds of disorders:
- Hyperkinesia- increase movement
- Hypokinesia- decrease movement
What species is knapweed poisonous to
Horses
What causes chewing disease in horses
Knapweed poisoning
what is symptoms are involved in chewing disease
- Impaired ability to eat and drink
- Confused behavior
- Mouth held open with chewing motions that can injure mouth or gums
- Starvation or dehydration
__inhibts dopamine transport in the equine brain in knapweed poisoning
DDMP
What cranial nerves are involved in knapweed posoining
CN V, VII, and IX
Injuries to cranial nerves V, VII, and IX results in ___ to facial muscles
Hypertonicity
Knapweed poisoning can cause lesions in what brain structures
Substantia nigra and globus pallidus
What structure in the brain compares intended movements to actual movements and makes adjustments
Cerebellum
Cerebellar lesions result in ___
Ataxia
Lesions to the cerebellar do not ___ or ___
Prevent movement or impair strength
What are the 3 regions of the cerebellum
Vestibulocerebellum, spinocerebellum, cerebrocerebellum
What is the vestibulocerebellum responsible for
Input from the vestibular nucleus that regulates balance and eye movements
What does the spinocerebellum do
Receives input from the muscles, skin and cortex. Enhances muscle tone and coordinates skilled voluntary movement, predicts position of the body in space during movement
What does the cerebrocerebellum do
Receives input from the primary motor cortex and plans and initiates voluntary activity, procedural memory
Which structure in the brain allows for unconscious control of fine motor movements
Cerebellum
What is the main output of the cerebellum
Motor cortex
The cerebellum receives inputs from what three things
- Cortex
- Vestibular system
- Muscle spindles
What is the molecular layer of the cerebellum
Represents the outer layer, sparse in cell bodies
What is the granule layer in the cerebellum
Inner layer of the cerebellum, rich in cell bodies
Small granule cells project their axons into the ___layer
Molecular
What layer has myelinated fibers that bring signals in and out
White matter
What are the large cells at the edge of the granule cell layer
Purkinje cells
What cells are the only output of the cerebellum
Purkinje fibers
Where are deep cerebellar nuclei located
In the white matter
What are the inputs for feed forward control of cerebellum
- Copy of the motor plan from the cerebral cortex
- Sensory information from the vestibular system, eyes, skin, joints and muscles
Integration: motor and sensory inputs are integrated to make an error correction and adjust posture
Describe the flow chart of cortex motor output to posture distributed
- Cortex motor output (UMN—>LMN)
- Body moves
- Posture is distributed
The cortex motor output is responsible for the ____of anticipated postural disturbances
Feed forward
The distribution of posture is responsible for the ___of unanticipated postural disturbances
Feedback
The feedback and feed forward mechanisms of postural disturbances result in
An adjusted posture
What is the input to the vestibulocerebellum
Vestibulosensory input from vestibular organ, superior colliculus, striate(visual) cortex
What is the output of the vestibulocerebellum
- Vestibulocerebellum
- Lateral and medial vestibular nuclei
- Vestibulospinal and bulbar tracts
What is the function of the vestibulocerebellum
Coordinate the movement of the head and eyes and control antigravity muscles
What is the result of dysfunction of the vestibulocerebellum system
Ataxia, poor balance, wide gate
What is the input to the spinocerebellum
Spinal and trigeminal sensory inputs, auditory inputs, striate (visual) cortex
What is the output of the spinocerebellum
- Spinocerebellum
- Interposted and fastigial nuclei
- Descending brain stem and corticospinal pathways
What is the function of the spinocerebellum system
Proper execution of coordinated movements
What is the result of dysfunction of the spinocerebellum system
Dysmetria, functional tremor, decreased muscle tone
What is the input to the cerebrocerebellum
Premotor, supplementary and primary motor cortex
What is the output of the cerebrocerebellum
- Cerebrocerebellum
- Den Tate nucleus
- Red nucleus sends output to ipsilateral olivary nucleus
- Motor and premotor cortices
What is the function of the cerebrocerebellum
Planning, initiation, timing, learning of motor skills and properly timed movement sequences
What are some symptoms of patients with cerebellar lesions
Wide gait, ataxia, dysmetria, asynergia, intention tremor, nystagmus, head bobbing
What is dysmetria
Inappropriate measure of muscle length. Movements continue for too long or too short; goose stepping. Typified by undershooting or overshooting intended targets
What is asynergia
Miscoordination of the components of a complex, multiple joint movements
What is an intention tremor
Oscillating movement that is more severe when an animal is moving or completing a movement
What is nystagmus
Eyes not coordinated
Where does the superior cerebellar peduncle cross
Casual midbrain level
Why would a cerebellar lesion prior to the decussation of the superior cerebellar peduncle cause an ipsilateral motor deficit
Because the ascending information from the lesion in cerebellum decussates to contra lateral side but descending information from UMN to LMN decussates back to ipsilateral side
If you have a lesion on the left cerebellum prior to the decussation would the motor deficit be ipsilateral on the left side or contralateral on the right side
Left side- Ipsilateral (same side)
What is canine multiple system degeneration
Fatal familial movement disorder
When does ataxia develop in canine multiple system degneration
3-6 months old
What are the severe symptoms of canine multiple system degeneration
Akinesia and severe postural instability
T or F: both the basal nuclei and cerebellum are affected in canine multiple system degeneration
True
What is bovine virus diarrhea virus
Transplacental infection of developing fetus in the first 6 months may result in various congenital malformations including neurological disorders
What is the most frequent neurological disorder in BVDV
Cerebellar hypoplasia
What is degenerated in cerebellar hypoplasia
Purkinje cells, loss of granule cell layer, resulting in a reduced cerebellum
Cats can develop cerebellar hypoplasia if they inherited or acquired what disease
Panleukopenia virus
T or F: panleukopenia can be transmitted across the placenta
True
What does panleukopenia attack that causes cerebellar hypoplasia
Attacks diving cells in outer layers of cerebellum
What are some symptoms of cerebellar hypoplasia
Intentional tremor, ataxia, wide gate, head bobbing
