3 Flashcards
1
Q
Spinal card organization
A
Spinal cord has the white matter on the outside while the gray matter is located inside.
The cell body of the sensory/afferent neuron is on the dorsal root ganglion which is located outside of the CNS.
Sensory information comes to the spinal cord from the dorsal root (posterior root) and it leaves from the ventral root (anterior root).
There is a posterior horn (towards the back and narrow) and an anterior horn (towards the front)
What connects the left and right side of the spinal cord is gray commissure.
2
Q
Three major sensory tracks
A
- Posterior column tract (dorsal column medial lemniscus DCML)
- Spinothalamic tract
- Spinocerebellar tract
3
Q
Chains of neurons
A
- First order neuron: Delivers sensation to CNS, their cell body is in the dorsal or cranial root ganglion
- Second order neuron: An interneuron with the cell body in the spinal cord or brain
- Third order neuron: Transmits information from the thalamus to the cerebral cortex
4
Q
Sensory tract organization
A
- Sensory modality: Fine touch sensations are carried in one sensory tract
- Somatotopic: Ascending tracts are arranged according to the site of origin
- Medial lateral rule: Sensory neurons that enter a lower level of the spinal cord are more medial within the spinal cord. Sensory neurons that enter at a higher level of the spinal cord are more lateral within the spinal cord.
5
Q
Brain mapping-homunculus
A
A cortical homunculus is a distorted representation of the human body, based on a neurological map of the areas and proportions of the human brain dedicated to processing motor functions, or sensory functions for different parts of the body.
The biggest areas of the brain dedicated to somatosensory and motor learning are in the hands and face.
6
Q
Gray commissure
A
It is what connects the left and right side of the spinal cord
7
Q
SAME DAVE
A
sensory afferent
motor efferent
dorsal afferent
ventral efferent
8
Q
Posterior column tract (dorsal column medial lemniscus DCML)
A
Transmits proprioception, fine touch, pressure, vibration to primary sensory cortex on opposite side of stimulus.
9
Q
Spinothalamic tract
A
Transmits pain and temperature sensations to the thalamus and then to the sensory cortex on opposite side of the stimulus
10
Q
Spinocerebellar tract
A
Transmits proprioception sensations to the cerebellum on same side of the stimulus.
11
Q
Brodmann areas
A
Primary motor cortex (4)
Primary somatosensory cortex (1,2 & 3)
Visual information- Posterior parietal cortex (7 & 5) Once the visual information is sent to the occipital lobe, it then splits into dorsal and ventral stream. The posterior parental lobe (Dorsal stream) is used as a secondary processing area of visual information.
12
Q
Signal detection theory
A
Is the ability to differentiate between a signal/stimulus and a random pattern that distracts us from the information.
concerned with the accuracy of responses
not under time pressure but less than 100% accuracy
un paced task
13
Q
Perceptual sensitivity D
A
Is the distance between the two means.
The larger the Perceptual sensitivity, the easier it is to differentiate between the two. There is going to be more correct decisions (hit and correct negative) and less errors (false alarm and miss).
The smaller the Perceptual sensitivity, the harder it is to differentiate between the two. There is going to be more errors (miss and false alarm) and less correct decisions (hit and correct negative).
- important to note that errors and correct decisions are related to one another.
- In order to do a task better, the perceptual sensitivity needs to be larger (the difference between the means need to be large).
Changes in D are due to environmental factors or individual differences
14
Q
Observer criterion B
A
The cutoff criterion can move right or left on the sensation axis and reflects the position of the cutoff axis
The position of the cutoff is determined by the performer and depends on his expectancies and the rewards and penalties in the situation
15
Q
Perceptual performance depends on
A
- Perceptual sensitivity of the performer
2. Expectancies about the performer and the rewards and penalties inherent in the situation
16
Q
Novice vs expert drives
A
- Novice drivers require a higher level of danger to be present before they are willing to respond to a hazardous situation
- No differences were shown in the sensitivity perception of hazardous situations
- For experts, this leads to the adoption of lax criterion, even though this means an increase in false alarms
Novices
hits: 50%
false alarms: 16%
Experts
hits: 84%
false alrams: 50%
17
Q
Discriminatory reaction time
A
concerned with time to respond with accuracy constant
100% accuracy if given sufficient time to response
forced paced task
It is the time it takes for a person to discriminate between two things.
The more alike the stimuli, the longer the DRT.
The easier the stimuli, the faster the DRT.
18
Q
Crossman’s confusion function
A
The law relating DRT (Discriminatory reaction time) to the degrees of discriminately of two stimuli.
It is basically a law that predicts the reaction time which is based on the similarity of two stimuli.
1. They need to be presented simultaneously
2. Can be measured along a physical dimension in terms of discriminability differences
19
Q
Pattern recognition
A
- Recognition of complex patterns relevant to a sport, differentiates skilled and unskilled athletes
- Fundamental perceptual abilities cannot explain skill differences
- Pattern recognition is critical for the success of skilled performers
Pattern recognition can be improved through perceptual learning
20
Q
Static and dynamic visual acuity
A
Static visual acuity is not related to performance is at least normal, but below average it may be a limiting factor
Dynamic visual acuity: There is a 0.3-0.4 correlation between dynamic visual acuity and performance but this is a very moderate relationship. However, dynamic visual acuity is still more important compared to static visual acuity in relation to performance.
SVA and DVA relate to innate abilities.
21
Q
Optical flow field
A
It is the expansion, contraction or regular movement of all the stimuli in the field of view.
22
Q
Time to contact (tau)
A
Cues associated with timing information about moving objects are crucial to a variety of activities
Timing information is needed to know when contact will occur
- Subjects could discriminate a time to contact difference of 150 ms with 90% accuracy
23
Q
Tau
A
Tau is the time to contact or time to collision between object and the observer and it is specified by the
size of image (on retina)/velocity of expansion of image (on retina)
Tau y (time until ball hits the ground)/Tau x (time until ball hits eyeballs)
- If the ratio is 1, then the ball intersects the eye
- if the ratio is more than 1, then the ball will land behind the fielder
- If the ratio is less than 1, then the ball will land in front of the fielder
24
Q
Decision making
A
This is a stage in the information processing model in which a response has to be selected.
It is between perception and the effector mechanism.
The decision making stage is still dealing with reaction time and not movement time.
25
Brain regions involved in decision making
- prefrontal cortex
- Striatum (Basal ganglion)
- pre motor cortex
26
Prefrontal cortex
The prefrontal cortex not only shows increased activity during decisions requiring self control, but during all decision making processes.
It is split between behavioural control and decision making
the neural interactions bw the dorsolateral and ventromedial prefrontal cortex not only play a central role when a person needs to decide between options during goal directed behaviour but also active during flexible decision making
27
Striatum (basal ganglion)
- It is part of the basal ganglia (which makes up the inner core of the brain) and processes both decision making and subsequent actions.
- There are two parts to it: putamen and caudate nucleus (head, body and tail) So putamen and caudate with its three parts make up the striatum
- Involved in reward based decision making, like eating food, drugs and etc
28
Premotor cortex
- it is part of the brodmann area 6
- It is an area of motor cortex lying in the frontal lobe, just anterior to the primary motor cortex. it is involved in planning of movements but also has other unknown functions.
- The premotor cortex decides what actions are desired, while the motor cortex decides how the actions are supposed to be carried
- Receives multiple sensory inputs, particularly visual, used to guide movements
- Influenced by cerebellum via thalamus
selecting movements based upon sensory cues, from a repertoire of possible movements.
damage impairs ability to plan strategies
input from posterior parietal cortex
not well understood
29
Supplementary motor area
- It is internally movements (self motivated)
- They are learned sequences like typing
- Associated with bimanual control
- Influences by basal ganglia via thalamus
planing of complex and 2 handed moves
coordinates posture
30
Summary
- prefrontal cortex plans
- premotor cortex sequences
- motor cortex executes
31
Choice reaction time
Is based on the idea that the number of stimuli and the responses that are based on the stimuli will affect your reaction time.
The more choices you are presented with, the slower your choice reaction time.
For an unskilled player, RT will be about 150 msec greater than simple reaction time. Now this is reduced or disappears for a skilled player.
32
Hick Hyman law
x: log 2 n
where n is the number of stimulus-response
The trained person will have a smaller slope and that is due to their training. A smaller slope indicates that they have a faster choice reaction time.
In this case, we are manipulating the choices we have.
The reason our slope decreases is because of practice, and so we bypass that limited information processing capacity that we have and instead we use the long term memory which is way faster.
33
Stimulus response compatibility
is though of as indicating degrees of practice on a particular configuration compared to another.
The higher the compatibility, the more the configuration has been practiced in our daily lives
- Stroop test is an example of S-R compatibility
34
psychological refractory period
psychological refractory period is the reason why faking works and why distraction is not good.
- Stimulus onset asynchrony (SOA) is the delay between stimulus 1 and stimulus 2.
- Slack is the delay of information processing when stimulus 2 is presented.
- If an action begins in response to a stimulus, then there is a delay of at least 100 msec in addition to the normal reaction time to respond to a second stimulus and this is only true if the second stimulus is presented within 50-200 msec after the first stimulus.
35
anticipation
Is using learned cues to predict future events.
| It is critical for success in open skills
36
Effector mechanism
This is the third stage of the information processing model.
The task of the effector mechanism is to organize motor system for the desired movements.
37
Control of voluntary movement
- Cerebral cortex
- Basal ganglia: controls position and the initiation of voluntary movement
- Cerebellum: Monitors muscles during movement
38
Three stages of movement
Stage 1: Prefrontal cortex plans the movement based upon information from the post parietal cortex about spatial perception (dorsal stream). Basal ganglion is also involved
stage 2: Secondary motor areas including premotor area and supplementary motor area work with the cerebellum to specify the precise sequence of contractions of the various muscles required.
stage 3: primary motor cortex, the brainstem and the spinal cord are all involved to produce the contractions of all the muscles needed.
39
Primary Motor cortex
Inputs: supplementary motor area, post parietal cortex, primary sensory area and premotor area
Outputs: Thalamus, cerebellum and basal ganglion
main area for executing voluntary movement
electrical stimulation produces movement
involved in the initiation and execution of movement
specify how actions are carried out
neurons in M1 fire immediately before and during voluntary movement
this neural activity encodes two aspects of the movement: direction and force
40
Levels of organization for movement
- Pre command: cerebellum and basal ganglia
- Projection: primary motor cortex and brain stem nuclei
- Segmental: Spinal cord and central pattern generator
41
Pre-command level
- cerebellum and basal ganglion
- regulate motor activity
- precise stop and start of actions
- block unwanted movements
- coordinate movements based on posture
- monitor muscle tone
42
Projection level
- Consists of upper motor neurons from motor cortex that initiate the direct pathway to produce voluntary skeletal muscle movements (also called the pyramidal tract or direct pathway)
- Brain stem motor areas- oversees the indirect pathway to modify commands of the direct pathway (also called extrapyramidal tract indirect pathway) modify ongoing actions
- Projection motor pathways send information to lower motor neurons and keep higher command levels informed of what is happening.
- brainstem areas oversee movements
- integrate visual and vestibular information
- helps control reflex and fixed pattern activities
43
Segmental level
- spinal cord
- lowest level of the hierarchy
- controls locomotion and repetitious moves
44
Motor cortex disfunction (lesions)
- paralysis
- hemiparesis
- monoparesis
45
Motor plan
An abstract representation of an intended movement
46
Supplementary motor cortex disfunction
| Premotor cortex disfunction
SMA: disrupt self initiated movements, impaired bimanual coordination, and alien hand syndrome
PMA: weakness of movements, and impair the movements elicited by sensory cues
47
Components of the basal ganglia
- Input: striatum (putamen and caudate nucleus)
- Output: globus pallidus (indirectly substantia nigra)
- At rest: subthalamic nucleus and substantia nigra
48
Functions of the basal ganglia
Voluntary control of movement: Initiation of voluntary movement, inhibits other movements, changes between movements, and adjusts movements while in motion.
Postural control: righting reflex and automated movements
Muscle tone control: Vestibulospinal
Chooses a particular movement or a sequence of movements out of many possible responses.
Controlled action requires both go and stop
Programs self initiated movements
Movement initiation: Processes internal triggers from memory to combine motor actions into routine.
Self initiated movement rather than stimulus triggered movement
Control of habitual, skill based behaviours
Planning and control of complex movements
Organize sequences of movements into smooth, automatic whole
49
Disorders fo the basal ganglia
Parkinson's disease (hypokinetic): Caused by neuron death in substantia nigra. loss of dopamine disrupts normal modulations of basal ganglion output.
Akinesia – difficulty initiating movement
Bradykinesia – slowness of movement
Rigidity – stiff inflexible limbs
Huntington's disease (hyperkinetic)
Chorea – unpredictable, involuntary movement
Ballism – flailing limbs, undesired motion
Athetosis – hand wringing
Tourte syndrome
Tics/tremors – Tourette Syndrome
Obsessive compulsive disorder
50
Cerebellum structure
- It contains more neurons than the total from the rest of the brain but it only takes up 10% of the total brain volume.
- The number of neurons in the cerebellum is related to the number of neurons in the cortex. There are about 3.6 times as many neurons in the cerebellum as in the cortex, a ratio that is true across many different mammalian species.
51
Function of the cerebellum
Responsible for fine motor movement, balance, Fine tuning movements and the brain's ability to determine limb position.
The cerebellum does not initiate movement, because it has no direct connection to motor neurons.
The cerebellum rather than the cortex plays an important role in learning and remembering of movements, also known as non-declarative/ procedural memory.
Contributes to coordination (assemble components of complex multi-joint or multi- limb movements.), accuracy of actions (uses sensory feedback to correct for errors in movement by comparing feedback to the intent of a “motor plan”), timing of actions (correct order and timing of individual muscle activation; timing of movements) and skill learning (acquire new motor skills).
receives input from sensory systems of the spinal and other parts of the brain and integrates these inputs to fine tune motor activity.
regulates movement and posture
52
Neuroanatomy of the cerebellum
* Cerebrocerebellum – input from cortex. Involved in planning and initiating movement.
* Spinocerebellum – input from spinal cord. Information about limb position and touch and pressure feedback. Useful for correcting or modifying movement.
* Vestibulocerebellum (Floculonodular lobe) – equilibrium, balance for posture
* Vermis – connects left and right hemispheres. posture, limb movements, eye movements.
53
Communication with the nervous system
Communicates with the rest of the nervous system via peduncles.
Peduncles connect cerebellum to brain stem at the level of the pons.
* Superior peduncle – primarily output. Connect to midbrain.
* Middle peduncle – primarily input from rest of brain. Connect to pons.
* Inferior peduncle – primarily input from spine. Connect to medulla oblongata
54
Cerebellar inputs and outputs
Inputs: motor cortex, inner ear, spinocerebellar tracts, muscle and joint proprioceptors
Outputs: Motor cortex, reticulospinal and vestibulospinal tracts, limb and postural muscles
55
Damage to cerebellum
Vestibulocerebellum –
- Loss of balance
- altered walking gait
- wide stance
Cerebrocerebellum –
- Problems with skilled movements: errors in
speed, force, direction, amplitude of moves
- Hypotonia, intention tremor, dysmetria,
ataxia
Spinocerebellum –
- Uncoordinated, poorly aimed movements
56
Disorders of the cerebellum
Ataxia: a lack of muscle coordination in voluntary movements. Can cause:
• Poor coordination
• Unsteady walk and a tendency to stumble
• Difficulty with fine motor tasks, such as eating, writing or buttoning a shirt
• Change in speech
• Involuntary back-and-forth eye movements (nystagmus)
• Difficulty swallowing
Dysmetria = Patients will “past-point” (i.e., reach past a target, or fall short of the target)
Intention tremor = (brought out by voluntary movement). Characteristically, the tremor is 1) more pronounced as the patient approaches the endpoint; 2) affects the shoulder and hip girdle muscles predominantly); and 3) the direction of the tremor is perpendicular to the movement of the limb.
• at rest there will be little or no tremor.
Hypotonia = very low muscle tone
57
Cerebral cortex
control of voluntary movements
language
personality
complex process- thinking, planning, decision making and creativity
58
Basal ganglion
Inhibition of useless movement
coordination of slow, sustained movements
inhibition of muscle tone
59
Thalamus
relay station for all sensory input
some awareness of sensation
role in motor control
60
cerebellum
maintenance of balance
coordination and planning of skilled movements
enhance muscle tone
61
Brain stem
cardiovascular, respiratory, and digestive control centres
regulate reflexes for equilibrium and posture
synaptic reception and integration from spinal cord
activation of cerebral cortex
role in sleep wake cycle
62
Information transmission to muscles
* Axons travel through Descending Tracts (Pathways)
* Some originate in cerebral cortex, others in spinal cord
* No synapses in the descending pathways.
* At destination the neurons synapse with a lower motor neuron.
Motor pathways usually contain two neurons
• Upper motor neuron - within CNS
• Lower motor neuron - from CNS to muscle
63
Descending tracts
All the neurons within the descending motor pathways are classed as upper motor neurons. Their cell bodies are found in the cerebral cortex or the brain stem, with their axons remaining within the CNS.
The motor tracts can be functionally divided into two major groups:
• Pyramidal tracts (Voluntary Movements)
• Extrapyramidal tracts (Involuntary Movements)
64
Pyramidal tracts
The name comes from the medullary pyramids of the medulla oblongata, which the axons pass through.
Origin: Cerebral cortex
Descend: they carry motor fibres to the brain stem and spinal cord
responsible for voluntary control of musculature of the body and face
Functionally, the pyramidal tract can be subdivided into two tracts:
Corticospinal tract: conscious control of skeletal muscle of the body
Corticobulbar tract: conscious control of skeletal muscle of the head and neck
65
Extrapyramidal tracts
They originate from the brainstem
They carry motor fibres to the spinal cord
responsible for the involuntary and subconscious control of all musculature, such as muscle tone, balance, posture and locomotion.
Vestibulospinal and Reticulospinal do not decussate, providing ipsilateral innervation.
Rubrospinal and Tectospinal do decussate, and provide contralateral innervation.
66
Summary of the role of descending tracts
The cerebellum is important in contributing to the motor system because it compares cerebral motor commands with proprioceptive feedback.
The corticospinal fibres that project to the ventral horn of the spinal cord have branches that also synapse in the pons, which project to the cerebellum.
The proprioceptive sensations of the dorsal column system have a collateral projection to the medulla that projects to the cerebellum.
these two streams of information is compared in the cerebral cortex
67
Red nucleus
Conflicts bw the motor commands sent by the cerebrum and body position information provided by the proprioceptors cause the cerebellum to stimulate the red nucleus.
The red nucleus then sent corrective commands to the spinal cord along the rubrospinal tract.
The red nucleus is a structure in the rostral midbrain
it is involved in motor coordination
the red nucleus is less important in primates than it is in other mammals
the crawling baby and the arm swinging during walking is controlled by the red nucleus.
the red nucleus plays a role in controlling muscles of the shoulder an upper arm. it has limited control over hands
the majority of the red nucleus axons relay information from the motor cortex to the cerebellum through the inferior olivary complex an important relay station in the medulla.
68
Lower motor neurons
They are located in the ventral horn of the spinal cord
they innervate the muscle and are organized functionally
axial motor neuron and muscles: move the trunk, important for maintaining posture
proximal motor neuron and muscles: move the shoulder, elbow, pelvis and knees. critical for locomotion
distal motor neuron and muscles: move the hands, feed and digits; specialized for the manipulation of objects
69
Motor units
motor neuron, motor axon and all the muscle fibres innervated by the motor axon.
the number of muscle fibres innervated will vary depending upon the muscle.
- gastrocnemius up to 2000 fibres
- eye muscles as few as 3 fibres
70
Motor neuron pool
all the individual motor neurons that innervate a signal muscle.
- each individual muscle fibre is innervated by only one motor neuron, but one motor neuron can innervate several muscle fibres.
- ratio of motor neurons to muscle fibres affects the precision of movement.
71
Corticobulbar tract
Corticobulbar tract: conscious control of skeletal muscle of the head and neck
- it receives the same inputs as corticospinal tract
- it descends to the brainstem
- Terminates on the motor neurons of cranial nerves. Synapses with lower motor neurons, which carry the motor signal to the muscles of face and neck.
- many of these fibres innervate motor neurons bilaterally
- eyes, chewing, tongue, expressions and speech
72
Vestibulospinal
Reticulospinal
Rubrospinal
Tectospinal
Vestibulospinal: receives input from vestibular system to control balance and posture by innervating anti gravity muscles (flexors of the arm and extensors of the leg)
Reticulospinal: Controls automatic locomotion and posture movements, automatic functions and muscle tone.
Rubrospinal: Originates from the red nucleus. primarily upper body. thought to play a role in the fine control of hand movements
Tectospinal: Originates in the superior/inferior colliculus
Coordinates movements of the head in response to bright light and sudden moves or loud noises.
73
Lateral tracts
| Medical tracts
Lateral tracts- control distal/ extremities (allow for fine motor control)
- corticospinal tract
- rubrospinal tract
Medical tracts-control axial muscles (posture, rhythmic movements)
- vestibulospinal tract
- tectospinal tract
- reticulospinal tract
74
Inputs to motor neurons
motor neurons can receive input from
upper motor neurons in the brain
sensory input from muscle spindles
input from spinal interneurons
75
Inputs to motor neurons
motor neurons can receive input from
upper motor neurons in the brain
sensory input from muscle spindles
input from spinal interneurons
76
Two effector control system
Predictability needs to be measured in relation to the skill level of the performer.
- Open loop system: it purely uses ballistic (unguided) movements. it is fast but cannot cope with a changing environment and depends on motor memories stored in LTM.
- closed skill
- skilled performance
- Closed loop system: it uses feedback to modify ballistic movements. it is therefore slower but it can cope with a changing environment.
- open skill
- unskilled performance
77
Feedback system (1 and 2)
Loop 1: is when the feedback comes from effector stage and goes back to the effector stage again.
- Alpha gamma co-activation system
Loop 2: is when the feedback comes from the effector stage and goes back to perception stage.
- delayed feedback
delayed auditory feedback- there is a reflexive but relatively slow (200 msec) auditory feedback system for controlling the muscles used for speech production.
this system is revealed by delaying feedback, this causes speech disruption.
- aimed movements
Fitts law relates movement time to the amplitude of the movement and the required accuracy.
this holds true for aimed movements that are made as quickly as possible.
78
Alpha gamma co-activation system
- functions to maintain smooth ballistic movements, stabilizing system for walking, picking up objects
- very fast (50 msec), reflex, therefore processes information without requiring conscious processing capacity
- this system is demonstrated by patellar tendon reflex. tendons are stretched in quadriceps muscle.
79
Fitts law
Fitts law relates movement time to the amplitude of the movement and the required accuracy.
this holds true for aimed movements that are made as quickly as possible.
the x is the index of difficulty
how can practice decrease the movement time to a target? make the movement time faster?
- More accurate muscle impulses would mean fewer corrections which take time-effector processing
- the visual feedback could be processed more efficiently- perceptual processing
80
Open loop systems
catching a ball or golf are examples of open loop.
| open loop uses parallel processing
81
Types of long term memory
- Declarative memory (experience and facts)
medial temporal lobe
sensory association cortex
hippocampus
- Non declarative memory
non associative: habitual, sensitization, reflex pathway
assosiative: amygdala, cerebellum and motor cortex
procedural memory: sensory and motor cortex, cerebellum and basal ganglia
82
Motor learning
Motor learning is an improvement of motor skills through practice, which produces long lasting neural changes
a more descriptive term is sensorimotor skills. Learning requires multiple receptions of a movement, usually under a variety of conditions.
83
Motor programs
- a representation in long term memory of a movement sequence that has been acquired through learning.
- it is the equivalent of chunking in perception
- can be run off without the need for feedback. so open loop control can be explained by the motor program.
- also, it can be one way to manage the degrees of freedom problem.
84
Measuring learning
- performance curve
- retention test
- transfer test
85
power law of practice
- individual curves are highly variable but are smoothed by averaging and can then be described by the power law of practice (learning)
- learning curves for a variety of perceptual motor tasks can be described by the power law of practice.
86
Motor learning problems
Performance plateau: no apparent improvement occurs in performance despite continued practice
degrees of freedom
- when teaching a skill, try to decrease the degrees of freedom in a situation.
there are three solutions to the degrees of freedom:
- movement efficiency- use mid range of joint angles
- smooth movements- minimize jerk (rate of change of acceleration)
- dependencies bw components of the motor system will reduce the degrees of freedom (synergy)
87
An aimed movement has two parts:
- an initial muscular impulse which leads to a ballistic movement toward the target. the ballistic movement is controlled by the muscle spindle system
- one or more visually guided corrections. this visually guided feedback is much slower and is an example of feedback loop 2.
88
Evidence for motor programs
- the effects of movement complexity on RT (more complex: slower RT)
- deafferentation experiments (block sensory information)
- blocking a limb during motion (EMG recordings similar)
89
How do we represent motor programs in our LTM?
- Invariant characteristics
relative force, relative timing, and order of movement components
- changeable parameters
absolute (overall) force, timing and spatial position
90
Lateral corticospinal tract
Decussates
descend into the spinal cord, terminating in the dorsal horn. then to the muscle of the body.
75-90% of voluntary movement.
91
anterior corticospinal tract
it remains ipsilateral
descending into the spinal cord
decussates and terminate in the ventral horn of the cervical and upper thoracic levels
10-25%
92
Researcher have observed
When the primary motor cortex activity is disrupted, errors in movement production occurs
when supplementary Motor area activity is disrupted, there are errors in sequencing movements
