Coordination

Question 1

What does controller do?

Answer 1

sets overall task and organizes feedback loops that assure stable task performance given the external conditions

So that controller doesn’t have to predict all internal and external sources of variability

Question 2

what does coordination require

Answer 2

spatial and temporal organization and relations among elements during a movement

Question 3

definition of coordination

Answer 3

ability to initiate, execute, and terminate a smooth, accurate, and controlled movement characterized by appropriate speed, amplitude, distance, direction, and timing

Question 4

synergy

Answer 4

• ability of units of action (DOF) to work together to achieve some goal
• loss of selectivity (fractionation) implies a problem in coordinating the DOF which results in problems of speed, amplitude, direction, smoothness, etc

Question 5

individuation/ fractioned movement

Answer 5

ability to selective activate a muscle, allowing isolated joint motion

Question 6

impaired individuation

Answer 6

• abnormal coupling between related muscles

- post stroke, active shoulder flexion = active elbow flexion

Question 7

within reaching tasks, what do cervical propriospinal neurons do?

Answer 7

• play a role in coordinating descending motor commands from motor cortical areas
• C3-C4 propriospinal system receives corticospinal, reticulospinal, and tectospinal input and afferent info from the limb that may facilitate activation of muscle synergies

Question 8

neural factors of fractionation

Answer 8

balance of descending fascilitory and inhibitory influences on segmental spinal processes –> hyper excitable brainstem pathways
peripheral afferent processes

Question 9

biomechanical factors of fractionation

Answer 9

• length of muscle (length-tension relationship, torque/angle = stiffness)
• moment arm influences
• relationship to gravity

Question 10

behavioral factors of fractionation

Answer 10

• practice

- habit

Question 11

influence of UE task on coordination

Answer 11

• pointing: all segments controlled as unit
• reaching: hand is “independently” controlled
• -sequential and subcomponents influenced by separate brain areas
• different velocity and acceleration profiles

Question 12

what does the neural control of reach and grasp require?

Answer 12

• conscious proprioception and object recognition

- localization (where the object is in space)

Question 13

conscious proprioception and object recognition for reach and grasp

Answer 13

• visual cortex to temporal cortex (visual stream) for conscious visual perceptual experience
• person with lesion in this stream has no consciousness of orientation or dimension of the object but can pick up the object with good dexterity

Question 14

localization required for reach and grasp

Answer 14

• visual cortex to PPC (dorsal stream)
• action relevant information about all phases of the reaching movement (may not require consciousness)
• PPC shows both motor and sensory activity

Question 15

PPC for reach and grasp

Answer 15

• movement planning or attention (goal and type of mvmt)
• lateral intraparietal: saccade planning
• medial intraperietal: planning of reach
• anterior intraparietal: planning of grasp

Question 16

medial superior temporal cortex in reach and grasp

Answer 16

planning smooth pursuits

Question 17

optic ataxia

Answer 17

• lesion to PPC
• problems reaching in correct direction
• positioning fingers or adjusting correct orientation of hand when reaching
• adjusting grasp to reflex size of object being picked up
• BUT CAN IDENTIFY AND DESCRIBE THE OBJECT

Question 18

What is visual feedback when reaching for?

Answer 18

attainment of final accuracy

Question 19

reaching across midline

Answer 19

• takes longer and is less accurate

* * clinical implication: understand this during exam and consider this in your progression of task complexity

Question 20

Somatosensory contributions to reach

Answer 20

• if movement is simple and non repetitive, humans can perform reach movement with vision occluded
• complex movements or repeated movement deteriorate quickly without visual feedback
• use of position sense when reaching comes mainly from spindle Ia afferents and cutaneous afferents

Question 21

what is essential for control of grip forces

Answer 21

cutaneous afferent input

Question 22

what detects a slip during a grasp

Answer 22

mechanoreceptors

Question 23

what occurs when fingers are anesthetized?

Answer 23

grip force increases

coordination between grip and load forces is lost

Question 24

What occurs to grip if person has only moderately impaired sensation?

Answer 24

coordination is preserves

Question 25

what occurs when S1 is inactivated

Answer 25

- uncontrolled grip and load forces and increased grip force | - S1 has slowly and rapidly adapting cells --> both respond to slipping

Question 26

what likely regulates hand path direction and spatial trajectory?

Answer 26

vision

Question 27

what facilitates terminal hand position and limb status?

Answer 27

proprioception

Question 28

what occurs to reach and grasp when object is in motion?

Answer 28

visual feedback from the moving object is of critical importance to predict synchronous grip and load forces in a timely manner (grip force is facilitated when vision is directed at object)

Question 29

descending pathways for reach and grasp

Question 30

Anticipatory control for grasping

Answer 30

pre-grasp hand shaping (under visual control) | anticipatory of characteristics of the object to be grasped

Question 31

what may influence the nature of control of limb synergies?

Answer 31

mechanical (structurally coordinated) linkages

Question 32

neural factors of incoordination

Answer 32

- typically attributed to function of cerebellum | - also includes motor and sensory systems and spinal cord

Question 33

cerebellum function is all problems of what?

Answer 33

metrics and timing

Question 34

musculoskeletal factors of incoordination

Answer 34

- generally not related to overall force generating capacity of the muscles involved - could be problems of force variability (maintaining it)

Question 35

Ataxia

Answer 35

loss of ability to control and coordinate movements

Question 36

ataxia in speech

Answer 36

dysarthria

Question 37

ataxia is often associated with:

Answer 37

- delays in initiation and execution times - dysmetria - dysdiadochokinesia

Question 38

cerebellar incoordination

Answer 38

- delays in initiation - dysmetria and intention tremor - dysdiadochokinesia - asynergia: errors in relative timing and amplitude of components of multisegmental movements (lack of smoothness in execution phase)

Question 39

hypermetria

Answer 39

less abrupt against burst | **prolonged agonist burst and delayed antagonist burst**

Question 40

hypometria

Answer 40

may have prolonged antagonist burst | co-contraction observed

Question 41

What does cerebellar damage result in and what does that mean to PTs

Answer 41

extend and rate at which individuals adapt movements | - longer training duration or intensity to improve performance

Question 42

cerebellum as comparator --> internal model concept describing function/dysfunction

Answer 42

- predicts sensory consequences of movement based on motor command - motor behaviors relay on prediction errors --> **perkinje cells**

Question 43

decomposition

Answer 43

- moving one joint at a time | - impaired multijoint coordination reflects role of cerebellum in anticipating and regulating **interaction torques**

Question 44

Impaired adaptation

Answer 44

- cerebellar's pathology reduces persons ability to adjust to novel loads through trial and error

Question 45

how is adaptation measured?

Answer 45

- object displacement in a dropped ball catch