Organization of the Motor System Flashcards
initiating and producing movement requires the interaction of what from where?
information from the senses and entire brain
what is the role of the motor cortex in movement
to plan and initiate
what is the role of the basal ganglia and cerebellum in movement
to coordinzte
what is the spinal cords’ role in movement
to send information to the muscles
what is the sequential production of movement of grabbing a cup?
1) visual info required to locate target
2) frontal lobe motor areas plan the reach and command the movement
3) spinal cord carries info to hand
4) motor neurons carry message to muscles of the hand and forearm
5) sensory receptors on the fingers send message to sensory cortex saying the cup has been grasped
6) spinal cord carries sensory information to brain
7) basal ganglia judge grasp forces, and cerebellum corrects movement errors
8) sensory cortex receives the message that the cup has been grasped
what brodmanns areas are given to the parietal cortex?
5 and 7
what is the role of the parietal cortex in initiating movement?
parietal cortex integrates information from the senses and initiates movements based on sensory information
what brodmanns areas are the prefrontal cortex?
9,10,11,45,46,47
what role does the prefrontal cortex have in initiating movement?
prefrontal cortex plans movements based on experiences, goals, and sensory input
what brodmanns area is the premotor cortex?
BA 6
what is the role of the pre motor cortex in initiating movement?
coordinates whole-body movements and organizes action sequences
what brodmanns area is the primary motor cortex?
BA 4
what is the role of the primary motor cortex in initiating movement?
produces simple movements, such as hand movements to use/manipulate tools
what are the 4 stages in initiating motor sequences?
parietal cortex sends goals –> prefrontal cortex plans–> premotor cortex sequences –> motor cortex executes actions
as movement complexity increases, __________ brain areas are _____ to coordinate the movement
additional, recruited
where does blood flood increase when participants tap their finger?
primary motor cortex and adjacent parietal cortex
where does blood flow increase when participants perform a motor sequence?
premotor cortex
where does blood flow increase when participants used a finger to navigate a maze?
prefrontal, temporal, parietal cortexes
electrical stimulation of which part of the brain triggered movements of different parts of the body?
precentral gyrus
stimulation to the cortex immediately ______ to the primary motor cortex also elicited movement
anterior
the motor homunculus is similar to what?
somatosensory homonculus
how is the body represented in the motor homonculus
upside down
where are the feet represented in the motor homonculus
central fissure
where is the head represented in the motor homunculus
near the inferior lateral surface
what areas of the body have the largest representations in the motor homunculus
mouth and hands, which are areas associated w fine motor control
which layer do modern techniques using microelectrodes penetrate to?
V
how many different possible homunculi are there in the motor cortex?
10
are all representations in the motor cortex mapped in the same way as the original example?
no
what do brief electrical stimulations produce?
movements of a specific body part
what types of behaviours do longer stimulations result in?
ethological behaviours
what are ethological behaviours
behaviors the animal might use in everyday activities
what are examples of ethological behaviours
defensive postures, hand to mouth, chewing, licking, hand in lower space, manipulate object in central space, reaching, climbing, leaping
what does a definition of an ethological movement include
the part of the body to be moved, the destination to which the movement is directed, and the function of the movement
organization of the homunculus is somewhat maintained by
the ethological movements
in terms of ethological movements, where are hand movements found in the homunculus
ventral
in terms of ethological movements, where are movements of hand to mouth found in the homunculus
most ventral
in terms of ethological movements, where are more complex whole body movements in the homunculus
premotor area
how can ethological movements be elicited?
stimulation of parietal cortex
stepping movements are triggered by
dorsal stimulation
hand movements are triggered by
ventral stimulation
movements evoked from parietal lobe map in a manner similar to those caused by what?
stimulation of the frontal lobe
mouth movements are triggered by
most ventral stimulation
what sort of sensory location about an object is needed to reach it successfully?
nature and locations
which movement is a developmental milestone for the first few months of life that gets refined over time?
pincer grip
damage to the cortical motor areas impair what?
the entire movement, not just the one part of the body or muscle that corresponds to the damage
movements to replace the impaired movement are controlled by what?
an intact part of the cortex, such as a pincer grip being replaced by a whole hand grip
evidence from stroke suggests that movements are encoded in
multiple areas of the cortex
damage to the primary motor cortex produces what?
muscle weakness and impairs individual movements
damage to the premotor cortex impairs what?
complex movemebts involving multiple body parts
what seems to be the role of the neocortex and motor planning areas
to involve blending prelearned movements like walking or climbing
in the experiment where monkeys flex their wrists to rotate a lever, what demonstrates that there may be motor cortex participation in planning?
neural activity increasing before movement
in the experiment where monkeys flex their wrists to rotate a lever, what does the neural activity continuing throughout movement suggest?
motor cortex participation in execution
in the experiment where monkeys flex their wrists to rotate a lever, what does the fact that neural activity increases over a no-weight condition mean?
that motor cortex neurons code force of movement
where are mirror neurons found
ventral premotor area
when are mirror neurons active
both when an animal is performing a movement and when it is observing someone else making the same movement
what types of mirror neurons are less specific and respond to broad classes of movements?
core mirror neurons
where have additional mirror neurons been identified?
temporal and parietal lobes
what does the basal ganglia include
caudate, pputamen, globus pallidus
where does the basal ganglia receive input from
the cortex and substantia nigra in the midbrain
what is the procedure of movement in the subcortical motor cortex
substantia nigra -> caudate -> thalamus -> cortex -> movement
what sort of damage do hyperkinetic symptoms result from?
damage to caudate and putamen
what are the dyskinesias involved in hyperkinetic disorders?
unwanted writhing and twitching movements
name some examples of hyperkinetic disorders
huntington disease, tourettes
how do hypokinetic symptoms come about?
result from loss of dopamine input from substantia nigra
what are hypokinetic symptoms associated with?
difficulty making voluntary movements
what is an example of a hypokinetic disorder
parkinsons
what does the combination of hypokinetic symptoms and hyperkinetic symptoms suggest about the role of the basal ganglia?
that it serves to modulate movement
where does the output of the interior portion of the globus pallidus (GPi) project to?
thalamus and motor cortex
what happens if the predominant input to the GPi is inhibitory?
then the region fails to inhibit the thalamus, and movement occurs
what happens if the predominant input to the GPi is excitatory?
then the GPi inhibits the thalamus, and movement is prevented
decreasing activity in the GPI decreases what?
symptoms of parkinsons
what is the direct pathway of regulating movement force within the cortex?
cortex to thalamus back to cortex to brainstem and spinal cord
what is the indirect pathway of regulating movement force within the cortex?
putamen, Gp external, subthalamic nucleus, GPi
what is the cerebellum important for?
acquiring and maintaining motor skills
what does the cerebellum include?
two hemispheres and a small horizontal lobe called the flocculus
describe the role of the flocculus
recieves info from the vestibular system and is involved in balance
midline areas of the cerebellum control what
midline of the body
lateral areas of the cerebellum are involved in what
movements of limbs and hands
what is the role of the cerebellum in movement?
timing movements, monitoring movement accuracy
damage to the cerebellum impairs what in terms of movement?
the ability to move at a regular rhythm and the ability to accurately perceive time
when distortion goggles were removed, patients with an intact cerebellum threw ____________________________________________, but patients with cerebellar damage were ____
incorrectly at the target and had to compensate, on target and did not have to correct
when the cortex sends a motor command to the spinal cord, where else does it send a copy
to the cerebellum
what type of sensory info is sent to the cerebellum
from the muscles and the visual system
how does the cerebellum go about adjusting movement?
compares the intention (motor output) with the results (the sensory input) and then generates a correction to achieve the desired results
which part of the cortex sends a copy of movement instructions to the cerebellum
inferior olive
where does the main motor pathway originate
in the motor cortex
what sort of information do the spinal cord pathways provide?
input about balance and posture to refine the movement commanded by the cortex
movements specified by the brainstem tend to be what?
coarse movements of the entire body
what does electrical stimulation of thebrainstem areas produce
behaviours such as arched back and erect hair in a cat, or walking or running behaviours
in terms of electrical stimulation of the brainstem, the timing of the behaviour depended on what
timing of the stimulation
in terms of electrical stimulation of the brainstem, the intensity of behaviour was determined by what
the magnitude of the stimulation
what is the role of the spinal cord in the chain of command to execute motion
the final pathway to convert motor plans into movements
corticospinal and corticobulbar tracts project from ____________ to ________
cortex to spinal cord
what to corticobulbar tracts control?
facial movements
what do corticospinal tracts influence
movement of the limbs, digits and body
where to corticospinal tracts originate
somatosensory areas, cortex, and pre motor cortex
where do corticobulbar and corticospinal tracts originate?
layer V of cortex
where do approximately 95% of the descending motor pathways decussate on?
ventral surface of the brainstem, resulting in a bump called the pyramids
what is true of the lateral corticospinal tract?
it decussates and influences the movements of limbs and digits CONTRALATERAL to the hemisphere where the motor command originated
what is true of the anterior corticospinal tract?
it does not decussate and controls the movements of the trunk
what does the lateral corticospinal tract move?
limbs and digits
what does the anterior corticospinal tract move?
muscles in the body’s midline
what structures provide the output connection between the nervous system and the muscles?
the motor neurons of the spinal cord
where do neurons from the corticospinal tracts synapse?
on both interneurons and motor neurons
what do lateral motor neurons influence
fingers and hand
what do intermediate motor neurons control
limbs
what do medial motor neurons control
the trunk
muscles that control the limbs are arranged into _____, ___________ and ___________
pairs, flexors and extensors
what do extensor muscles do
move limb away from trunk
what do flexor muscles do
move limb toward the trunk
what is the neurotransmitter at the neuromuscular junction
ach
