Behavioral Speed

1
Behavioral Speed

• Speed reduction in reaction affects all aspects
  of ones life
• takes longer to groom, dressing, daily chores,
  driving behavior, accident rates at home?, change
  out of pocket
• Some CNS changes can be measured by Speed of
  Response
• Reaction Time - time interval from onset of
  stimulus to initiation of response
• Simple reaction time-one stimulus, one response
• Choice reaction time-when there is a choice

2
Can exercise muscular training contribute to
maintenance of motor control

• Human movement based on some minimal level of
  muscular strength, endurance, flexibility
• CNS more vulnerable to oxygen inadequacy than
  other physiological systems
• Cortical tissue cannot survive without oxygen for
  more than 5-10 min
• Maintenance of oxygen delivery system would seem
  highly appropriate preventative behavior to
  postpone premature aging (Spirduso, 1995)

3
Risk for Falling

• Impaired balance, slow inadequate postural
  adjustments to changes in the environment, poor
  leg strength, compromised locomotor patterns,
  escalate the risk of falling

4
Coordination Skill in Complex Movements

• Complex movement/muscle patterns require practice
  before skill
• Coordination (define) - ability of eyes, hands
  feet to accomplish goal
• Integration of vision and hands while performing
  task eye-hand coordination
• Perceptual schema - internal model of environment
  and input parameters
• Motor schema - programmed to activate the
  appropriate muscles to complete task

5
Sensory Function Related to Motor Control

• Information from the environment
• Sight, sound, smell
• Sensations from the body
• Touch, proprioception, pain, temperature
• Receptors in these systems provide info re type
  of modality activated (sight, sound, smell) and
  intensity, duration, and location of the
  stimulus.
• Sensory systems most closely related to motor
  control are

6
Vision

• Vision provides information about
• Environment and location, direction and speed of
  movement of individual
• Visual and vestibular input trigger postural
  reflexes to maintain balance and prepare for
  movement
• Associated w/aging are losses in
• Visual processing speed
• Dynamic vision
• Visual search
• Size of visual field
• Estimation of velocity
• Acuity in low illumination
• Accomodation reserve
• Resistance to glare

7
Vision

• Other changes occur
• Ability to detect the spatial relationships of
  objects
• Depth perception
• Peripheral vision
• All contribute to balance

8
Exercise Effects on Vision

• Little to no research has been conducted on the
  effects of acute and chronic exercise on eye
  physiology and visual function in either young or
  old adults
• What do you think?
• Type II Diabetes -? leads to retinopathy one of
  the 3 leading causes of blindness

9
Vestibular Function

• Control postural sway
• Receptors provide a static vertical reference to
  position head with respect to gravity
• Vestibular neurons decrease in both number and
  size with age (starting at age 40)
• By 70 yr, 40 of sensory cells of system are lost
  effect on function is equivocal
• Depends on when (how old subjects are in study

10
Motor Skill Classification

• Discrete movements - recognizable beginning and
  ending point
• Unilateral, bilateral, repetitive, sequential,
  aiming
• Continuous motor skills
• Tracking, handwriting
• Multilimb skill
• Driving an automobile
• Functional skills
• Fine motor card sorting, typing, using eating
  utensils, dialing a phone, picking up coins,
  squeezing toothpaste, zipping a garment
• Gross-motor shoveling, mopping, sweeping,
  ironing, throw

11
Other Movements

• Continuous movements - No distinguishable break
  in motion (no obvious beginning or end)
• Steering wheel of car, writing
• Handwriting speed - declines with age - 60y
• Specificity of training
• Multilimb coordination - right hand control
  maintained better - neurological redundancy in
  left-hemisphere

12
Age Effects on Physical and Behavioral Attributes
Necessary for Driving

• Vision - 90 of information
• Dynamic acuity, acuity, size of useful visual
  field, detection of motion in depth, detection of
  angular motion
• Eye-hand-foot coordination
• Compensatory changes in behavior of older drivers
• Drive significantly less
• Take fewer risks
• Drive more slowly
• Avoid driving in bad weather

13
Learning Physical Skills

• Older subjects learn simple skills relatively
  quickly - the gap narrows with the young quickly
• Tasks with continuous series of complex and
  varied movements, more difficult to learn in
  middle age and older adults
• Reminiscence

14
Neural Plasticity Mechanism for Learning

• Older adults cannot eliminate age differences in
  many coordinated motor performances with
  extensive practice
• Number of active motor units decreases with aging
• Motor performance can be improved
• Brain has ability to change structure function

15
Morphological Changes with Practice

• New contacts and neurochemical changes that
  facilitate specific pathways are developed by
  practice
• Changes in number, cell structure, and density of
  neurons accompany physical activity in animals
• Size principle (Henneman et al., 1965)
• The fore and speed of contraction dictate the
  recruitment pattern and firing rate of motor
  units
• Oxygen availability may influence the recruitment
  of high threshold motor units
• Moritani et al, 1992 speculated that when
  skeletal muscle contractility is reduced due to
  occlusion, muscle spindles and golgi tendon
  organs signal for recruitment of more motor units

16
Morphological Changes with Age

• Neurons die
• Dendritic branches, thin and lose interneuronal
  contact
• Brain weight becomes lighter

17
Reflexes

• Reflex sets of elementary patterns of
  integration activated or modified by sensory
  stimuli or descending influence from brain stem
  or cerebral cortex
• Stretch reflex
• Flexor withdrawal reflex
• Righting reflex
• Myotatic reflex Achilles tendon reflex
  monosynaptic contributes to control of sway
  during standing and balance during locomotion
• Reflexes represent neural integrity