voluntary motion Flashcards
cortical areas associated with the production of voluntary motion
- primary motor cortex
- supplementary motor cortex
- premotor cortex
- pre-frontal cortex
- parietal cortex
What enables us to complete motor acts based on visual input?
dorsal visual pathway that contains axons from the occipital cortex to the parietal/frontal cortex
Where is information relayed to from the visual cortex?
parietal cortex: V6A, PEc, MIP, and VIP
PEc
caudal area PE of posterior parietal cortex
MIP
medial intraparietal area
VIP
ventral intraparietal area
role of VIP in voluntary movement
creates a rough map of the space around you
Where is the info sent from the VIP?
to F4 within the premotor cortex
role of F4 in voluntary movement
creates a detailed map of the space around you
What are neurons in F4 excited by?
proximity
What receives info from the visual cortex about where you are in space?
superior parietal cortex V6a
Where does the superior parietal cortex send info?
F2 in the premotor cortex
role of F2 in voluntary movement
map of location of your arm in relation to your body and things around you
response role of anterior intraparietal area and PFG
- seeing an object to grasp
- grasping an object
- both seeing and grasping an object
Where do anterior intraparietal area and PFG relay info?
to F5
What do F5 neurons fire for?
the GOAL of the action, not the action itself
Is a visual pathway required for reaching and/or grasping an object?
yes - dorsal visual pathway
Are areas of parietal cortex required for reaching and/or grasping an object?
reaching: V6a, PEc, MIP, VIP
grasping: AIP cortex, PFG
Is the creation of maps required for reaching and/or grasping an object?
reaching: yes
grasping: no
What creates the map of space (with object) for reaching?
VIP - rough
F4 - detailed
What creates the map of body for reaching?
F2
Is awareness of the goal required for reaching and/or grasping an object?
reaching - no
grasping - yes, via F5
Is the encoding of motor act required for reaching and/or grasping an object?
no for both
What is the role of the premotor cortex in voluntary motion?
- receives the sensory information required to move (F4 and F5)
- dorsal - applies rules that determine whether it is appropriate to move
- ID the intent of moving and decides what motion to produce
“is it ok to move?”
“ID motion required to meet goal”
divisions of the supplementary motor cortexx
- supplementary motor area (SMA)
- pre-supplementary area (pre-SMA)
role of SMA in voluntary motion
postural control
role of pre-SMA in voluntary motion
plans the motor program required to make the action occur
role of supplementary motor cortex in voluntary motion
- organize motor sequences
- acquire motor skills
- executive control (particularly the decision to switch actions/strategies)
“posture”
“ID specific sequence required”
“changes tactics”
role of primary motor cortex in voluntary motion
- precentral gyrus
- controls specific movements
- regions of body that do fine motions have proportionately higher representation
- arranged in columns
“codes individual motions required to reach the goal”
What does stimulation of a column produce?
specific movement
fine motor control is more likely to be contraction of ____
a single muscle
a column that produces a general motion, such as a movement in your back, may be the contraction of ____
a group of muscles
What layer of the primary motor cortex receives sensory input (muscle and joint proprioceptors)?
layer 4
What layer of the primary motor cortex is the output for the corticospinal pathway?
layer 5
What are the functions of the 2 sets of neurons in each column?
one to start the motion, and one to maintain the motion
neighboring columns control _____
related motions
What are the two kinds of columns?
- on/off for agonist muscle
2. on/off for antagonist muscle
role of the cerebellum
- sequence complex actions
- correct force/direction
- balance and eye movements
- learning of complex actions
spinocerebellum
vermis: postural control
paravermis: force and direction
cerebrocerebellum
lateral regions
-plan complex motions and sequence
“playing music”
vestibulocerebellum
- balance and eye movements
- future planning
Where do outputs from the cerebellum go?
deep cerebellar nuclei: dentate nucleus, fastigial nucleus, interpositus - globose and emboliformis
inputs to central region of spinocerebellum
vestibular
visual and auditory
efferent copy (what brain sends to muscle)
central region of spinocerebellum function
postural adjustments to ongoing motions
outputs to central region of spinocerebellum
interpositus nucleus
fastigial nucleus
rubrospinal tract
lateral regions of spinocerebellum function
correct ongoing motions and control ballistic motions
inputs to lateral region of spinocerebellum
muscle afferent efferent copy (what brain sends to muscle)
outputs of lateral region of spinocerebellum
interpositis nucleus
rubrospinal tract
function of cerebrocerebellum
sequencing of rapid movements and planning of complex motions
inputs to cerebrocerebellum
all regions of cerebral cortex
outputs of cerebrocerebellum
dentate and cortex
function of vestibulocerebellum
control of eye movement and balance, particularly in the future
input of vestibulocerebellum
vestibular apparatus
output of vestibulocerebellum
fastigial nucleus to vestibular nuclei
ascend or descend
role of the basal ganglia
planning and programming of movement
initiation of movement
how do basal ganglia work?
inhibition and withdrawal of that inhibition (to start movement) called “excess of GABA”
nigrostriatal path
from SNPC
- tonically active
- dopaminergic
- to striatum
What receptors are in the direct pathway?
Excited by?
Motion?
- D1
- dopamine
- allows motion
What receptors are in the indirect pathway?
Excited by?
Motion?
- D2
- EAA/Ach
- inhibits
striatonigal pathway
- GABA-ergic
- axons from striatum project to the SNPR and GPi
- presynaptic terminal releases GABA in the SNPR and GPi
- inhibition of the neurons in the SNPR and GPi
- “direct pathway”
direct pathway
- SNPC releases dopamine within striatum (nigrostriatal pathway)
- axons from the striatum project to the SNPR and GPi
- those axons release GABA
- axons from the SNPR and GPi project to the thalamus and release GABA
indirect pathway
- axons from the striatum project to the external segment of the Globus Pallidus and release GABA
- axons from the GPe travel to the subthalamic nucleus and release GABA
- axons from the subthalamic nucleus travel to the SNPR and GPi and release EAA
- axons from the SNPR and GPi travel to the thalamus and release GABA
intrastrialtal cholinergic system
- between nuclei of the striatum
- effects: excitatory
- excites indirect pathway
How is the indirect pathway activated?
- intrastriatal cholinergic pathway
2. EAA inputs from the cortex
prefrontal cortex voluntary motion functions
- planning of complex motor actions
2. carrying out of “thought” processes
how does the prefrontal cortex plan complex motor actions?
interacts with parieto-temporal-occipital association area and all levels of motor cortex and cerebellum
What areas are required for the planning of complex motion?
- frontal association area
- supplementary motor cortex
- premotor cortex
- cerebrocerebellum
Interactions between what areas determine IF motion will occur?
- frontal
- premotor
- SMC
- basal ganglia
What steps must happen prior to the primary motor cortex being activated?
- plan
- sequence
- “approved”
Where do action potentials travel from the primary motor cortex?
down axons of pyramidal cells and activate the alpha-motor neurons that innervate muscles needed to complete motion
What opposes every motion we make?
muscle spindle
How does the brain oppose the opposition from muscle spindles?
using gamma-motor neurons to “trick” the muscle spindle sensitivity so that the muscle spindle doesn’t change its firing rate despite a change of overall muscle length
- actives alpha-motor neurons + gamma motor neurons of the agonist
- inhibits alpha motor neurons + gamma motor neurons of antagonist
What makes sure the motion is correct one the motion has started?
spinocerebellum
