11.3 Flashcards
Basal Ganglia, Cerebellum, and Movement
What are some of the roles of the basal ganglia?
Associative learning, motivation, emotion, motor control (force)
What are the structures that make up the basal ganglia?
Caudate nucleus, putamen, subthalamic nucleus, and the globus pallidus
What is the term some use to group together the caudate nucleus and the putamen?
the Striatum
From where does the basal ganglia receive input?
All areas of the neocortex and allocortex; the nigrostriatal pathway from the substantia nigra
Where does the basal ganglia project to?
The motor cortex and the substantia nigra
What structure is the Striatum connected to? (outside of the basal ganglia)
The amygdala
What happens is the cells of the caudate nucleus are damaged?
Unwanted writhing/twitching movements (dyskinesias)
What disorders are related to the basal ganglia?
Huntington’s, Tourette’s (hyperkinetic); Parkinson’s (hypokinetic)
What are hyperkinetic symptoms?
Excessive involuntary movements; stemming from damage to striatum; BG is excessively excited
What are hypokinetic symptoms?
Paucity of movement, as seen in Parkinson disease; damage to BG; BG is insufficiently excited
What is the volume control theory? (aka volume hypothesis)
The basal ganglia can influence whether movement occurs by modulating the amount of force that is involved with the initiation of a movement
What is the direct pathway of the basal ganglia?
- the cortex activates the putamen
- Putamen inhibits the GPi
- The inhibited GPi is unable to inhibit the thalamus
- The thalamus releases motor commands to the cortex and spinal cord
In the cortico-basal ganglia-thalamo-cortical loop, the direct pathway ______ behavior whereas the indirect pathway _______ behavior
releases; inhibits
What is the indirect pathway of the basal ganglia?
- Cortex activates the Putamen
- Putamen inhibits the GPe
- GPe can no longer inhibit the Subthalamic nucleus
- STn excites the GPi
- GPi is able to inhibit the Thalamus
- With Thalamus inhibited, action ceases (no more motor commands to cortex or spinal cord)
What controls whether the putamen inhibits the GPi or the GPe? How?
SNc (D1 or D2 receptors); receptor activation depends on the amount of dopamine in the Putamen
What are “the yips?”
Distorted execution of skilled movements by professional athletes, proposed to be caused by impairments to the globus pallidus
What are the two main functions of the cerebellum?
Timing of movement and movement error correction/accuracy
What are the three lobes of the cerebellum?
Anterior, posterior, floccular
What is the role of the anterior lobe of the cerebellum?
Helps us maintain posture, where we are in space
What is the role of the posterior lobe of the cerebellum?
Precise movement and inhibiting involuntary actions
What is the role of the floccular lobe of the cerebellum?
Eye movement, where in space eyes are moving, maintaining balance with where eyes are projecting
Summarize the cerebellum’s topographic organization
Homunculus like motor cortex; the trunk of represented in the its central part, the limbs and digits are represented in the lateral parts
What are the output cells of the cerebellum?
Purkinje cells
What structure of the brain controls rapid updating and correction (moment-to-moment learning) AND long-term motor learning?
The cerebellum
How is information sent to the cerebellum from the cortex?
Via the inferior olive
How is information sent to the cerebellum about feedback from a movement?
Via the spinocerebellar tract
The ______ contribute to motor control by adjusting the ______ associated with each movement
Basal ganglia; force
Damage to the BG results in either unwanted involuntary ______ movements (too much force exerted) or in such ________ rigidity that movements are difficult to perform (too little force exerted)
Hyperkinetic; hypokinetic
The cerebellum contributes to motor control by improving movement ________ and the learning of motor _______
accuracy; skills
Describe how the cerebellum improves execution of motor skills.
The cerebellum compares an intended movement with the actual movement, calculates any necessary corrections, and informs the cortex to correct the movement
