PHYS: Voluntary Motion Flashcards
What areas are associated with the control of voluntary motion?
The dorsal visual pathway contains axons from the occipital cortex that travel to the parietal/frontal lobe and this input allows us to:
Complete motor acts based on visual input
Ex. catching a ball
What does VIP (ventral intraparietal area) do?
Creates a rough map of the space around you
What does F4 do?
What are they excited by?
Creates a detailed map of the space around you.
Proximity (the closer the object, the more likely to fire)
Where is F2 located? What does it do?
In the premotor cortex
Map of Body
It is the end result of the dorsal pathway (reaching), and constructs a related map of where your arm is in relationship to your body + the things around you
What is the order of the dorsal (reaching) pathway?
- Visual cortex
- VIP (rough map)
- F4 (detailed map)
- F2 (related map pf body + space)
The anterior intraparietal area + PFG are involved in what pathway? They respond to what neurons?
Grasping
Visuomotor Neurons (need to see + motor)
What is the function of F5 neurons?
They fire w/ the goal of the action (no motor)
What is the pathway for grasping an object?
- PFG/AIP
- F5
- sends sensory info required to move to premotor cortex
Both, grasping + reaching an object are what visual pathway?
Do these encode a motor act?
Dorsal visual pathway
No
This pathway applies the rules that determine whether it is appropriate to move
What is the function of the premotor cortex?
It identifies the intent of motion and decides what motion to produce.
Determins whether itis okay to move
What two divisions make up the supplementary motor cortex?
- Supplementary motor area (SMA) - postural control
- Pre-supplementary area (Pre-SMA) - plans the motor program required to make the action occur
(sequence of motion)
Organizing motor sequences acquireing motor skills, + executive control = what area?
Supplementary Motor Cortex
The primary motor cortex does what?
Codes the individual motions required to reach the goal.
Its arranged in 6 columns –> stimulation of any given column produces a specific mvmt (greys anatomy brain surgery)
Which layer of the primary motor cortex recieves sensory input?
4
Which layer of the primary motor cortex becomes the output for the corticospinal pathway?
Layer 5
What 2 sets of neurons are found in each column?
One to start motion
One to maintain motion
What do neighboring columns contain?
Related motions
What are the 2 kinds og columns?
- = on/off agonist muscle
- on/off antagonist muscle
What is the role of the cerebellum in producing voluntary motion?
Sequencing complex actions
Correct force/direction
Balance + eye movements
Learning of complex actions
What is the spinocerebellum responsible for?
central - postural control
vermis - force + direction
ballistic motions
What is the cerebrocerebellum responsible for?
Sequence (ex. steps of a surgery, muscians) + plan complex motions + learning
Future balance + eye mvmts is taken care of by?
Vestibulocerebellum
Input: Vestibular
Output: Vestibular n.
Vestibulocerebellum
What are the inputs + outputs for cerebrocerebellum?
Input: cerebral cortex related to motion
output: dentate n.
Inputs + outputs for spinocerevellum (lateral):
Imput: efferent copy + muscle afferent info
Output: Interpositus
Spinocerebellum (vermis) iputs + outputs:
Imputs: efferent copy, vestibular, hearing + auditory input
output: interpositus + fastigial n.
How does the basal ganglia aid in voluntary motion?
How?
They help initiate mvmt + plan and program it (control beginning + end)
Via inhibition (GABA) + withdraw of that inhibition
What is the nigrostriatal path in the basal ganglia?
It goes from SNPC (substantia niagra pars compacta) –> Striatum
Tonically active
Has dopamine (indicates 2 pathways)
Which basal ganglia pathway uses D1 vs D2?
D1 = Direct
D2 = Indirect
What is the direct pathway?
D1 receptors
Excited by dopamine
Allows motion
What is the indirect pathway?
D2
I = inhibts motion when active
Inhibited by dopamine
Excited by EAA/Ach
Describe the striational GABA-ergic pathway:
Direct pathway
Describe the indirect pathway:
-which step is excitatory (EAA)
-subthalamic nucleus –> SNPR + GPi
To produce motion we must: ______ the direct pathway + _______ the indirect pathway.
activate direct
inactivate indirect
Review:
How do we inhibit motion?
By activating the indirect pathway via the intrastriatal cholinergic pathway
Planning of complex motor actions + carrying out of “thought” processes happens where?
Prefrontal cortex
In order to plan complex motor actions, what area gets involved?
Parieto-temporal-occipital association area + motor cortex (supplementary motor cortex + premotor cortex) + cerebrocerebellum
Interactions between the frontal, premotor, SMC, and the basal ganglia determine:
IF the motion will occur
Once the motion is planned + approved, columns in the primary motor cortex are activated and carry the action potentials of the pyramidal cells to the alpha-motor neurons to innervate the muscles needed to complete the motion.
The brain activates the alpha AND gamma motor neurons so that the muscle spindle doesn’t change its firing rate. To stretch the muscle, they BOTH will be inhibited.
Once motion has started, what is called upon to make sure the motion is correct?
Spinocerebellum
