Motor Learning Across the Lifespan: Lecture 3

Question 1

Development of postural control

Answer 1

• Head to pelvis
• dynamic alternating advancement and regression
• Reflexes integrated into functional, voluntary motor responses
• Initially driven by visual system

Question 2

Posture at certain ages

Answer 2

15 months
- compensatory postural responses are present but more variable and slow

3 years
- predominance of visual control of balance shifts to somatosensory control
- refinements in sensory aspects of postural control continue

7 to 10
- postural responses basically adult like

Question 3

Intrinsic/extrinsic factors of aging and postural control

Answer 3

Intrinsic factors
- genetics
- health status
- lifestyle

Extrinsic factors
- environment
- stress
- lifestyle

Question 4

Aging and postural control

Answer 4

Impaired reactive control with delays and smaller response magnitudes causing abnormal timely activation for postural responses

Delayed anticipatory response which will then change voluntary movement task (open car door and fall backward)

Decrease ankle responses (more hip-dominated responses)

Increase sway and LOB due to reduced/distorted sensory input

Bending at knees, using arms to balance

Question 5

Development of sensory systems

Answer 5

• visual system takes several months from birth to develop acuity
• vision helps to calibrate vestibular and proprioception
• development of otolith function could be key contributor to emergence of walking
• <11 y/o difficulty substituting vestibular/somatosensory systems for visual

Question 6

Sensory system changes with aging

Answer 6

• decrease in tactile and vibratory sensitivity (loss of receptors)
• decrease % of sensory fibers innervating peripheral receptors
• changes in visual system
• reduction in vestibular system function (loss of 40% vestib hair and nerve cells by 70)

Question 7

Reach and grasp at certain ages

Answer 7

4-6 years
- make mvmt w/o visual feedback with reasonable accuracy
- gradual changes in anticipatory grasp and lifting from 4-11 y/o

7 years
- abrupt reduction in ability to make mvmt w/o visual feedback
- transition causing children to return to more visually dependent FB

10-11
- reach and grasp at adult levels
- anticipatory control of grasping/lifting at adult levels
- dual task control at adult levels by 15

Question 8

Aging and reach and grasp

Answer 8

• reaching velocity reduce 30-90%, slower speed at end of reach
• rely of slow FB process aka vision
• decrease in hand steadiness
• decrease in manual dexterity
• decrease in precision grip force control, force output when grasping (UE strength importance)

Question 9

Development of gait

Answer 9

Postural control vital for development of walking to control COM

3 requirements
- rhythmic stepping pattern (refined w/in first year)
- control of balance (stability)
- ability to modify gait (adaptation)

2368 steps and 17 falls per hour when learning to walk

Question 10

Aging and gait

Answer 10

• temporal/distance factors (decrease velocity, step length/rate, stride length/width, swing phase; increase stance phase, time in double support)
• increase coactiviation/stiffness
• more time to monitor visual environment
• kinematic changes (decrease vertical mvmt of COG, arm swing, all joint flexion, flatter foot on heel strike, dynamic stability during stance)
• decrease power generation at push-off and power absorption at heel-strike
• fear of falling, attentional problems