Voluntary Motion Flashcards
What are the cortical areas associated w/ the production of voluntary motion ?
Primary motor cortex
Supplementary motor cortex
Pre-motor cortex
How does pre motor cortex participate in the control of voluntary motion?
Receives SENSORY INFO needed to move and decides what motion to produce
Applies RULES, is it OK to move??
What are the 2 division of the supplementary motor cortex?
SMA
Pre-SMA
How does SMA participate in the control of voluntary motion?
Postural control
How does pre-SMA participate in the control of voluntary motion?
Plans motor sequences and has exec. Control over the TACTICS/strategies to use
What are the three functions of the supplementary motor cortex?
Organize motor sequences
Acquire motor skills
Executive control (decision to switch actions/strategies)
Where is the primary motor cortex?
Pre central gyrus
What is highly represented on the pre central gyrus?
Controls regions of body that do fine motions(i.e. Hands)
What does the primary motor cortex get particularly excited by?
Specific movements that are related to moving arms/hands INTO the face(mouth) or body
How is the primary motor cortex organized?
Into columns
Neocortex arranged into columns, made up of 6 layers
What does layer 4 of the neocortex contain?
A layer of synapses that receives sensory info from the specific muscle assoc. w/ column
Sensory info - muscle and joint proprioception
What does layer 5 of the columns in the primary motor cortex do?
Output for CST pathway to go down SC
What do a subset of CST axons synapse on?
What are these called?
Can synapse on alpha MN controlling Muscle assoc. w/ column
Subset = pre-motor neuron (a UMN)
What are the 2 sets of neurons found in each columN
One STARTS motion
One MAINTAINS motion as long as necessary
What does stimulation of any given column produce?
A specific movement
To control a fine motion, the column would stimulate ___?
Contraction of a SINGLE muscle
To control a general motion, the column would stimulate ___?
Stimulate GROUP of muscles for contraction
What do neighboring columns have in common?
Control related MOTION
Not necessarily Ms.
What are the 2 kinds of columns?
- On/off for agonist
2. On/off for antagonist
What does the primary motor cortex code for?
Individual motions required to reach the goal
What is the dorsal visual pathway?
Occipital cortex —> parietal/frontal cortex
Helps us complete motor acts based on visual input
What does reaching require info about?
About OBJECT’s location
How is info for reaching real eye?
Visual cortex —> Parietal cortex, V6a, PEc, MIP, VIP —> VIP makes ROUGH map —> F4 makes Detailed map
What does the Vental intraparietal area do?
Makes rough map of space around you
Where if F4 found?
Within the premotor cortex
What does F4 do?
Creates DETAILED map of space around you
What excites the neurons within F4?
Excited by proximity of objects
CLoser you are, more excited they get!!
What is the info relay system for your own body position?
F2 in the premotor cortex
What is the pathway for info about your body position?
Visual info about where arm is —> superior parietal cortex —> F2 in pre motor cortex
What does F2 do?
Creates a related map of where your ARM (or other body part) is in relationship to body and things around you
What does Grasping info about?
Info about what you INTEND on doing and the FEATURES OF ITEM
Gs = Goal and Grasping
What is the info relay system for grasping?
AIP and PFG —> F5 —> Goal of action
Will stimulation of F5 produce a motor act
No
If neurons in the AIP and PFG are excited just by seeing an object to grasp, what do we call them?
Visually dominant
If neurons in the AIP and PFG are excited just grasping an object, what do we call them?
Motor dominant
If neurons in the AIP and PFG are excited by seeing AND grasping an object, what do we call them?
Visuomotor neuron
Why are there different F5 neurons?
Different ones for different goals
I.e. sipping from a cup vs. carrying a bunch of cups
What is the role of the cerebellum?
Sequence complex actions
Correct force/direction
Balance and eye movements
Learning of complex actions
What are the 2 regions within the spinocerebellum?
Vermis
Paravermis
What is the Vermis in control of?
Postural control of ONGOING motions
What are the inputs to the vermis?
Vestibular
Visual and auditory
Efferent copy
What are the outputs of the Vermis regions?
Interposed nuclei
Fastigial nucleus
RuT
What is the Paravermis region of the SPinocerebellum for?
Correct force and direction of ONGOING motion
Control of BALLISTIC Motions
What are the input to the paravermis region?
Msucle afferent (force and direction)
Efferent copy
What are the outputs of the paravermis region of the spinocerebellum?
Interposed nuclei
RuT
What does the cerebrocerebellum do?
PLAN complex motions and sequence of them
NOT ONGOING
What are the inputs to the cerebrocerebellum?
All regions of cerebral cortex
NO EFFERENT COPY
What are the outputs of the cerebrocerebellum?
Dentate
Back to cortex
What makes up the vestibulocerebellum?
Flocculus
Nodule
What is the vestibulocerebellum for?
Balance/eye movements; for FUTURE movements
What are the inputs to the vestibulocerebellum?
Vestibular apparatus (direct or indirect)
What are the outputs of the vestibulocerebellum?
Fastigial nucleus —> vestibular nuclei
Will then ascend or descend
What causes Myasthenia Gravis?
Anti body against the nicotinic cholinergic R. Located at the motor end plate
What does the LGN do?
Begins early processing of the visual imaging at an UNCONSCIOUS level
What does the ventral pathway do for a visual image?
Naming/identifying objects in field of vision
What does the dorsal pathway do for a visual image?
Transmits visual image to MOTOR and Sensory cortices for ACTION
What is dopamine that is made in the vetnral tegmental area for?
For emotions
What is the dopamine made int he substantia nigra made for?
Motor control
What is the dopamine made in the hypothalamus made for?
Endocrine control
What are D1 receptors associated with?
Causing what?
Gs —> increase cAMP —> increase excitability of neuron
What are D2 receptors assoc. w/?
Gi —> decrease in cAMP —> decrease in neuronal excitability
What are D1-like receptors?
D5
What are D2 like receptors?
D3 and D4
What does spasticity result from?
Overactive gamma motor neurons that makes msucle spindle hypersensitive
Causes overactive response to a passive motion
What could cause over active gamma motor neurons?
Damage to brainstem’ s inhibitory region
Facilitatory regions are dominant and will produce too much gamma MNs
What control the walking motion?
A central pattern generator in the SC
What is a Central Pattern Generator?
Collection of neurons whose output controls/generates a motor act that needs to be repeated over and over to be effective w
What kinds of motions are controlled by CPGs?
Examples?
Rhythmic, stereotyped and modifiable motions
Are more complex that reflexes but less than voluntary
EX.: breathing or walking
What does sensory info do to the CPG?
Can modifying the action occurring
Where it’s he general location of the CPG for walking?
Spinal cord
The CPG for walking is under control of what?
Voluntary control that checks if it is OK to walk right now and what the GOAL is
Priamry motor cortex and cerebellar regions = significant role in activated walking CPG
What will sensory info to the walking CPG make sure of?
Makes sure walking motion is appropriate to the environment that I am walking in
What happens when we take away sensory input to the CPG?
CPG slows down walking pace
What is the normal mechanism of activation of the CPG?
Cortex
What do we see regarding the walking CPG in patients w/ spinal cord injuries?
Sensory info can initiate activity of CPG
How are postural adjustments to walking made?
Require descending influences of cortex and cerebellum
NOT CONTROLLED BY CPG
What is the funciton of basal ganglia?
Involved in planning and programming of movements
Input impt. To initiate movement
Controls beginnings and end of movement
Said basically, how do basal ganglia work?
By inhibition and de-inhibition influences
“excess of GABA”
What is the direct pathway also called?
Striatonigal GABA pathway
What parts of the thalamus are inhibited by basal ganglia?
VA and VL
What does the cortex release to act on striatum in the indirect pathway?
From what tract?
EAA and ACh from intrastriatal tract
What is the receptor on striatal neurons in the direct partway?
D1 - assoc. with Gs - induces excitability
What is the receptor on striatal neurons in the indirect pathways?
D2 - assoc. w/ Gi - hyperpolarization
What is the cause of Parkinson’s?
What are the 2 resutls of this?
Subst. Nigra Pars Compacta input is abolished
- Direct pathway hard to activate
- Indirect pathways is overactive
What cortex is Association with voluntary motion?
Prefrontal cortex
What are the 2 functions seen iwth the prefrontal cortex
Judgment
- Plans complex motor actions
- Carries out thought processes
Interaction with what regions of the brain determine IF motion will occur?
Frontal, premotor, SMC, and basal ganglia
What does the prefrontal cortex interact with for voluntary motion to occur?
W/ parieto-temporal-occipital association area and all levels of the motor cortex and cerebellum.
Frontal assoc. area, supplementary motor cortex, premotor cortex and cerebrocerebellum
Once a motion is planned, sequenced and approved what will be activated in order to initiate movement?
Columns in PMC
How do you get from columns —> muscles?
APs down axons of pyramidal cells to alpha MNs —> ms.
What is the role of alpha-gamma co-activation int he production of voluntary motion?
Voluntary motion requires that if the
Brain activates the alpha MN, it must also activate the Gamma MN for spindles in contracting muscle (agonist)
And vice versa
Why do the alpha and gamma need to be co activated?
Bc muscle spindle will oppose motion, bc the muscles are being stretched.
Gamma comes in and reduces the sensitivity of the msucle spindles in antagonist muscle
