Behavioral Speed

1. Behavioral Speed Speed reduction in reaction affects all aspects of one�s 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 Discrimination reaction time - if the subject is told that something might happen, just the uncertainty as to whether it will happen increases reaction time SRT - requires low-level CNS processing - no integration, no calculation, no decision-making represents the general responsiveness of the CNS Slowing of SRT is considered one of the most measurable and recognizable behavioral changes that occurs with aging Fozard, etal. 1990 - SRT slowed 0.6 ms a year from age 20-96 Adding one decision increased the slowing rate to 1.5 ms/year CRT - includes3 components: the perceptual process of identifying the stimulus; the decision process; and the motor process required. The first and last are relatively stable. Middle component, the processing of the stimulus-response code and selection of motor response that varies with the complexity of the choices to be made See page 190Discrimination reaction time - if the subject is told that something might happen, just the uncertainty as to whether it will happen increases reaction time SRT - requires low-level CNS processing - no integration, no calculation, no decision-making represents the general responsiveness of the CNS Slowing of SRT is considered one of the most measurable and recognizable behavioral changes that occurs with aging Fozard, etal. 1990 - SRT slowed 0.6 ms a year from age 20-96 Adding one decision increased the slowing rate to 1.5 ms/year CRT - includes3 components: the perceptual process of identifying the stimulus; the decision process; and the motor process required. The first and last are relatively stable. Middle component, the processing of the stimulus-response code and selection of motor response that varies with the complexity of the choices to be made See page 190

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) Medical issues: loss of motor control may evoke: -loss of mobility -increased risk of falling & subsequent injury -loss of independence, leading to high cost of health careMedical issues: loss of motor control may evoke: -loss of mobility -increased risk of falling & subsequent injury -loss of independence, leading to high cost of health care

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 Eye-hand coordination is defined as the �skillful , integrated use of the eyes, arms, hands, and fingers in fine, precision movement� Sewing, playing video games, slicing a carrot, turning a knob to change a radio station - all have to be learned and require eye-hand coordination. A schema is a set of rules by which decisions are made. A perceptual schema is a set of rules by which environmental and internal information is identified, organized, and classified. A motor schema is a set of rules that integrates perceptual schema and recalls or initiates motor commands to activate the appropriate muscles in the correct sequence. So what happens when we try for the first time a complicated movement pattern? Answer: Jerky, poorly timed sequence of individual movements that requires a substantial amount of energy.Eye-hand coordination is defined as the �skillful , integrated use of the eyes, arms, hands, and fingers in fine, precision movement� Sewing, playing video games, slicing a carrot, turning a knob to change a radio station - all have to be learned and require eye-hand coordination. A schema is a set of rules by which decisions are made. A perceptual schema is a set of rules by which environmental and internal information is identified, organized, and classified. A motor schema is a set of rules that integrates perceptual schema and recalls or initiates motor commands to activate the appropriate muscles in the correct sequence. So what happens when we try for the first time a complicated movement pattern? Answer: Jerky, poorly timed sequence of individual movements that requires a substantial amount of energy.

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: Visual, vestibular, & proprioceptive systems (vibration, touch, limb and body position, detection of force)Visual, vestibular, & proprioceptive systems (vibration, touch, limb and body position, detection of force)

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 Losses in vision affect balance and locomotion as well as coordinationLosses in vision affect balance and locomotion as well as coordination

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 Discrete movements are measured by their reaction time. Older people generally preprogram, program and reprogram movements the same way that young people do, just more slowly. Aiming movements - ones that are fast and require accuracy. Fitts� law specifies that the more difficult the movement to be made, the slower it is made. That is, movements to hit small targets that are far away from each other take longer to execute than movements to hit larger targets close to each other. An aiming movement is made more difficult by making the target smaller or by increasing the length of the movement. When the task requires both speed and accuracy, the individual must make a choice. Biomechanics/kinematics analysis looks at acceleration phase, steady-state phase, and deceleration phase or homing-in phase. Young subjects accelerate more rapidly but have a longer deceleration period. Movement times are not different. Older subjects have more difficulty controlling force especially braking movements. (CNS-controlled reciprocal coordination of agonist and antagonist muscles.Discrete movements are measured by their reaction time. Older people generally preprogram, program and reprogram movements the same way that young people do, just more slowly. Aiming movements - ones that are fast and require accuracy. Fitts� law specifies that the more difficult the movement to be made, the slower it is made. That is, movements to hit small targets that are far away from each other take longer to execute than movements to hit larger targets close to each other. An aiming movement is made more difficult by making the target smaller or by increasing the length of the movement. When the task requires both speed and accuracy, the individual must make a choice. Biomechanics/kinematics analysis looks at acceleration phase, steady-state phase, and deceleration phase or homing-in phase. Young subjects accelerate more rapidly but have a longer deceleration period. Movement times are not different. Older subjects have more difficulty controlling force especially braking movements. (CNS-controlled reciprocal coordination of agonist and antagonist muscles.

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 Older adults have declines in visual processing speed, dynamic vision and visual search.. Performance is worse in dim light. Driving also involves psychomotor skill. In addition to the above skills, one needs long and short term memory, motor programming during information processing, decision making under stress Decline in ability to attend selectively to specific task-relevant stimuli. Must be able to divide perceptual-motor task (the controls) and active visual search for information in unpredictable locations. Older adults have accidents due to the slowness with which they make decisions and their inability to rapidly discriminate relevant information from irrelevant information Become more field dependent as we age. Less likely to detect signs and symbols in the background. Should there be an age ceiling for driving an automobile? Older adults have declines in visual processing speed, dynamic vision and visual search.. Performance is worse in dim light. Driving also involves psychomotor skill. In addition to the above skills, one needs long and short term memory, motor programming during information processing, decision making under stress Decline in ability to attend selectively to specific task-relevant stimuli. Must be able to divide perceptual-motor task (the controls) and active visual search for information in unpredictable locations. Older adults have accidents due to the slowness with which they make decisions and their inability to rapidly discriminate relevant information from irrelevant information Become more field dependent as we age. Less likely to detect signs and symbols in the background. Should there be an age ceiling for driving an automobile?

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 Reminiscence is defined as a gain in performance that occurs following a rest between trials. Although very few analyses have been made of age effects on working skills, even complex motor skills can be maintained will into the later years. Berkshire Community College � tennis class � Tanglewood � summer home of the Boston Symphony � teaching tennis � violin player Reminiscence is defined as a gain in performance that occurs following a rest between trials. Although very few analyses have been made of age effects on working skills, even complex motor skills can be maintained will into the later years. Berkshire Community College � tennis class � Tanglewood � summer home of the Boston Symphony � teaching tennis � violin player

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 Practice means that you are developing neuronal circuit activityPractice means that you are developing neuronal circuit activity

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