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S2 Movement Science > Motor Control IV > Flashcards

Motor Control IV Flashcards

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1
Q

prehension

-what is required to perform this?

A

know target location
reach
grasp
manipulation

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2
Q

prehension: reach
- what is it?
- how is it done?
- guided by…

A

transport hand to target so digits align with target

  • produced primarily by proximal musculature
  • guided extrinsically by target (distance, location)
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3
Q

prehension: grasp
- what is it?
- how is it done?
- guided by…

A

pre-shaped digits; opens them to match target size

  • produced primarily by distal muscles of hand and fingers
  • guided by intrinsic properties of target (size and shape)
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4
Q

manipulation

-what is it

A

carrying out target’s intended use

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5
Q

role of vision in prehension

A

vision is key for accurate prehensino

  • determines environment regulatory conditions in which the action with occur: distance/location; size, orientation
  • person needs to look directly at object for grasp = point of gaze
  • enables corrections that occur just before grasp
  • binocular vision aids grip size and force of grip
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6
Q

reach (at normal speed) is under _____ loop control

-why?

A

closed

-visual information (feedback) is used constantly during reach and grasp

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7
Q

Two-Stream Hypothesis

  • composed of two…
  • -what are they?
A

composed of 2 distinct visual systems

  • ventral stream
  • dorsal stream
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8
Q

ventral stream

  • what part of brain?
  • function
  • vision for…
  • described as the _____ pathway
A 
visual cortex --> temporal lobe
provides relevant information about physical properties of the object being reached for
-shape, size, orientation
vision for perception
described as the "what" pathway
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9
Q

dorsal stream

  • what part of brain
  • function
  • vision for…
  • describes as the _____ pathway
A

visual cortex –> posterior parietal cortex
provides action-relevant information about all phases of reaching movement
vision for action
describes as the “where” and “how” pathway

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10
Q

perception vs. action

-size extimation vs. grasp of 2 circles with different external areas that make them appear to be different sizes

A

discs estimated to be different sizes

grip aperture equal

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11
Q

reach
-FMRI data suggests existence of…
-

A

a map related to movement planning in posterior parietal cortex (PPC)

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12
Q

reach FMRI data

-separate sensorimotor transformation areas for…

A

smooth pursuit eye movements
reach
grasp

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13
Q

reach: PPC
- involved in…
- output to…

A

involved in encoding goals for movement

output to premotor and primary motor cortex

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14
Q

what computation does the brain need to make for accurate reach?

A

coordinates of hand and object
-object coded relative to eyes (visual)
-hand coded relative to body (somatosensory)
timing of postural response (APA)
inertial properties of the limb
encode kinematics and kinetics of movement (permotor and primary MC)
-efference copy to cerebellum

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15
Q

first sign of voluntary reach and grasp is at what age?

A

around 4 months

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16
Q

postural support of reaching

  • key brain structure
  • requirements or _____ dependent
  • -explain
A

key brain structure for learning of anticipatory postural adjustments during bimanual task is the cerebellum
task-dependent
-requirements in supported sitting are < standing and postural demands for stand and reaching are greater and require greater activation of LE and trunk musculature to prevent instability
-postural demands can affect speed and accuracy of UE

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17
Q

EMG during prehension (reach and grasp)

  • order of muscle firing
  • head moves _____% of way to target
A

neck muscles fire first (20-40 ms) before (due to increased inertia of head) eyes, and then arm (eyes can move alone if target is within central visual field)

  • in a coordinated movement of eyes and arm - we look to the target that is selected to grasp
  • typically, head moves 60-70% of the way to target
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18
Q

arm has _____ muscle program

-brief explanation

A

tri-phasic

-agonists-antagonists for breaking and then agonist

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19
Q

pointing vs. reaching to grasp

-control of UE movements

A

pointing
-segments controlled as a unit
reach to grasp
-hand controlled independently of arm, with arm carrying out transport; hand carries out grasp and manipulation

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20
Q

pointing vs. reaching to grasp

-velocity profile and movement duration

A

reaching movement duration > pointing movement duration
grasp an object; acceleration phase < deceleration
hit a target: acceleration phase > deceleration

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21
Q

reach transport phases

-what are the phases

A

acceleration and deceleration

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22
Q

perhension is different from pointing/aiming task because…

A

person intends to use the object to achieve some type of goal
reach has acceleration and deceleration phases

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23
Q

prehension: reach and grasp

- requires coordination of what components?

A

wrist/hand transport
grip aperture: pre-shaping and closure
hand orientation

24
Q

grasping kinematics

  • hand preshaped during…
  • max grip aperture (distance between thumb and index finger tip) occurs within _____ of movement completion
  • scaling of max grip aperture traces correlated to…
A

hand preshaped during movement to target (object)
max grip aperture occurs within 60-80% of movement completion
scaling of max grip aperture traces correlated to object size

25
Q

factors that affect grip aperture size

A

faster reach-grasp movements –> larger maximum grip apertures
-grasp at normal speed vs. grasp “as fast as possible” without dropping the object
–376 ms for fast speed
–735 ms for normal speed
larger maximum apertures were observed for the faster movements
-reach-grasp movements that start with an open grip aperture show a tendency of the hand grip to partially close before achieving its maximum aperture

26
Q

2 requirements for successful grasp

A

hand adapted to size, shape,a nd use of object (pre-shaping)

finger movements must be times appropriately for open/closure

27
Q

2 primary grasp/grip patterns

A

power

precision

28
Q

power grasp pattern

  • explain
  • types of grasps
A 
finger and thumb pads directed toward palm to exert force on object
types
-hook
-spherical
-cylindrical
29
Q

precision grasp pattern

  • forces directed between…
  • allows for _____ that power does not
A

forces directed between the thumb and fingers

allows movement of object relative to hand and with the hand (power does not)

30
Q

precision grasp pattern

-types of grips

A

3-jaw chuck (tripod)
pinch (pad to pad, tip to tip)
lateral pinch

31
Q

sensation and grasp

  • what are of brain is responsible for cutaneous input?
  • what would happen without this?
A

primary sensory cortex

without it –> uncoordinated grip and uncoordinated forces

32
Q

with slippery objects, cutaneous receptors detect…

  • as a result…
  • what patients will have difficulty with this response
A

detect slip
-activate motor activity to increase grip force in finger muscles
patients with sensory neuropathy

33
Q

control of hand posture relation to regulation of contact force

A

separate but not independent because hand must be shaped properly so the correct set of fingers makes contact with the object

34
Q

fMRI study of brain regions demonstrate that ____ and _____ signal level of grip force prediction through _____

A

caudate and anterior putamen signal level of grip force prediction through
-cortex, ventral thalamus, cerebellum (efference copy/corollary discharge/reafference)

35
Q

slippage

-_____ sensation

A

cutaneous sensation

36
Q

evolution of normal and tangential forces with finger pad contact on glass

A

increased grip forces

“stick” decreases with increased tangential forces

37
Q

adaptation of grip forces

  • with age
  • with loss of sensation
A

aging
-decreased manual dexterity with larger grip forces
loss of sensation
-larger grip forces, no matter the weight or texture of the material

38
Q

application to prosthetic hand

A

a five-fingered prosthetic hand consisting of digits driven by DC motors

  • force sensor resistors (FSR) placed at fingertip and potentiometers attached at proximal and middle joints
  • information from FSR can detect level of normal force exerted and also slippage between fingers and object
39
Q

development of prehension

-phases

A

phase 1
-infant reaches with one hand when they see an object
-once infant makes manual contact with object, vision facilitates hand closure (grasp)
phase 2
-infant uses 2 hands to acquire an object; child attempts different type of grasps
-role of vision in grasp to close hand decreases; switches to tactile stimulation

40
Q

infants reaching for rattle in dark and light

-effect on prehension

A

prehension enhanced if infant views their own hands

41
Q

prehension in infants (at 1 week)

-when does grasp formation develop

A

can reach for and intercept moving object, but hand is wide open - grasp formation which develops around 10-22 weeks

42
Q

prehension at 4 months

A

prehension controlled proximally; poor contact with object

43
Q

prehension at 5 months

A

prehension controlled distally; contact orients hand to object

44
Q

prehension at 6 months

A

squeeze emerges (fingers close around object)

45
Q

prehension at 9 months

A

prehension controlled by thumb and 1 finger (pincer grip); hand orients before contact
pre-shapes for object size
poor adjusting grip force

46
Q

prehension at 13 months

A

fingers oppose action of thumb without hand being stabilized

47
Q

prehension at 18 months

A

child can release the object

48
Q

if object is scaled to hand size, grasp is similar to adult pattern as early as age…

A

6-7 years

49
Q

age and prehension

-characteristics of young

A

infant can intercept moving objects; able to predict where an object will be which is anticipators
thumb opposition at 7 weeks
children open hands wider
children have increased variability
grip formation not mature until around 7 years

50
Q

age and prehension

-characteristics of elderly

A

30% decrease in speed of reach
more time in target deceleration phase
accuracy is about the same for drawing tasks, just slower
20-40% increase in time to do fine manipulation skills by age 70
most decrements are reversible with practice

51
Q

neural subsystems contributing to reach and grasp

  • function of peripheral receptors
  • visual input divided into…
A

tells you what’s happening around you, where you are in space, and where your joints are relative to each other
-visual input is divided into 2 parallel paths

52
Q

neural subsystems contributing to reach and grasp: function of…

  • higher cortical centers
  • basal ganglia
  • cerebellum
  • descending paths
A

higher cortical centers make movement plan
basal ganglia plans forces to grasp
cerebellum refines movement
descending paths activate spinal cord neurons to muscles

53
Q

prehension open loop control

  • when is it used
  • this control takes advantage of…
A

anticipate requirements of task and obstacles that might perturb arm trajectory and correct for effects of perturbation
anticipatory control takes advantage of previous experience to predict consequences - occurs before sensory receptors are stimulated and reduces reliance of feedback

54
Q

prehension closed loop control

A

feedback from vision and proprioception needed at end of movement to ensure hitting target accurately

55
Q

systems theory

-predicts…

A

predicts specific neural and musculoskeletal subsystems that contribute to control for reach, grasp and manipulation

56
Q

patient application: reaching across body for object

  • difficulty
  • how might this effect your treatment plan
A

visual processing is more complex
-reaching a target on opposite side is slower and less accurate than movements to target on same side as arm
when you
when you examine a patient, consider where you have the target and for your intervention, you may want to begin ipsi reaching prior to progressing to contra reaching

S2 Movement Science (13 decks)

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