Lecture 19: Voluntary Motion and Basal Ganglia Flashcards
What cortical areas are associated with voluntary motion?
- Primary Motor Cortex
- Supplementary Motor Cortex
- Pre-Motor Cortex
- Parts of Pre-frontal Cortex
- Parietal cortex
Redundant Roles
What does the premotor cortex do?
- Receives sensory information required to move
- Determines the appropriate motion and intent of the motion (dorsal part)
Identifies goal and motion required to meet goal
What does the supplementary motor area of the supplementary motor cortex do?
Postural control
What is the pre-supplementary area of the supplementary motor cortex involved in?
Plans motor program required to make the action occur
What does the supplementary motor cortex?
- Postural Control
- Organize motor sequences
- Acquire specific motor skills (with cerebellum)
- Executive control (decision to switch actions/strategies)
What does the primary motor cortex do?
- Controls specific movements of the body to reach goal
- Fine motions have high representation
What does layer 4 of the primary cortex do?
Receives sensory input from muscles and joint proprioceptors
What does layer 5 of the primary motor cortex do?
- Output for corticopsinal tracts: axons will travel down spinal cord (UMN)
- If axons synpase with alpha motor neuorns, they are known as pre-motor neurons
What sets of neurons are found in each column of the primary motor cortex?
- Start motion
- Maintain motion as long as necessary
How are columns organized in the primary motor cortex?
Neighboring columns have similar motions
- Also agonist/antagonist columns are nearby each other
What is the visual pathway required for both reaching and grasping?
Dorsal visual pathway
How does the brain receive visual information required for reaching?
Visual information is relayed to specific areas of the parietal cortex:
- V6A
- PEc
- MIP
- VIP
What does the ventral intraparietal (VIP) area do?
What action is it involved in?
Creates a rough map of space around you and desired object
Reaching
Where does the VIP area send its information to?
F4 areas within in pre-motor cortex
What does F4 do?
How does it do it?
How does the F4 region create a detailed map of the space around you?
Create a detail map about the space around self.
Neurons in F4 are excited by proximity: more activity the closer the desired object is
Where does the super parietal cortex send information to?
What information is it sending?
F2 area of the pre-motor cotex
Visual information about where your arm is in space
What does the F2 area do?
Creates a map about the location of arm in relationship with body and objects around self
What actions are the anterior intraparietal area and PFG of the parietal cortex responsive to?
Seeing an object and grasping it
Where does PFG/Anterior intraparietal area relay their information to?
F5 of the pre-motor cortex
What does the F5 area do?
Respond to goal of the action
(Intended goal: to drink the tea, how it is held is not important)
What are the functions of the spinocerebellum?
- Vermis: Postural Control
- Paravermis: Force and direction
- Correct ongoing motions and control ballistic motions
What are the functions of the cerebrocerebellum?
Plan complex motions and sequencing them
What are the functions of the vestibulocerebellum?
Balance/eye movements
What structures transmit the output from the cerebellum?
Deep Cerebellar Nuclei
- Dentate
- Emboliform
- Globose
- Fastigial
What are the inputs and outputs to the vermis of the spinocerebellum?
- Input: Efferent copy (what berrain sends to muscle), vestibular, auditory input
- Output: Interpositus and Fastigial Nuclei to rubrospinal tract
What are the inputs and outputs to the paravermis of the spinocerebellum?
- Input: Efferent copy (what berrain sends to muscle) and muscle afferent
- Output: Interpositus Nuclei to rubrospinal tract
What are the inputs and outputs of the cerebrocerebellum?
- Input: Cerebral cortex relating to motion
- Output: Dentate nucleus back to cortex
What are the inputs and outputs of the vestibuloocerebellum?
- Input: Vestibular Apparatus
- Output: Fastigial nucleus to vestibular nuclei
What does the basal ganglia control?
Control beginning and end of the movement
To produce motion, we must ____ the direct pathway and ____ the indirect pathway
Activate
Inactivate
What is the direct pathway to initiate movement?
- Step 1: D1 receptors on striatum excited, releasing GABA
- Step 2: GPi and SNPR is inhibited, reducing GABA release
- Step 3: VA/VL nuclei of thalamus is no longer inhibited, increasing thalamic activity and releasing EAA
- Step 4: EAA excites motor cortex –> MOTION
What happens to do the indirect pathway when motion is trying to occur
- Step 1: D2 receptors in striatium is inhibited, reducing GABA released
- Step 2: Globus Pallidus Externus is no longer inhibited, releasing GABA
- Step 3: Subthalamic nuclei is inactivated, reducing EAA released
- Step 4: GPi is inhibited with lack of EAA exciting it
Rest of pathway is direct
How does the indirect pathway stop motion?
- Step 1: Striatium is excited, releasing GABA.
- Step 2: Globus Pallidus Externus is inhibited, reducing GABA release.
- Step 3: Subthalamic nuclei is no longer inhibited, releasing EAA.
- Step 4: Globus Pallidus Internus is activated, releasing GABA.
- Step 5: Thalamus is inhibited –> NO MOTION
To make motion occur, what is the brain’s action on muscle spindles in the antagonist muscle?
Inhibits alpha-motor neurons and gamma-motor neurons
