Exam 2 Study Guide
Exam 2 Study Guide HK 44300
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This 5 page Study Guide was uploaded by Fayette Adelaja on Sunday October 25, 2015. The Study Guide belongs to HK 44300 at Purdue University taught by Jeffrey Haddad in Fall 2015. Since its upload, it has received 40 views. For similar materials see Neuroscience of Movement in Human Development at Purdue University.
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Date Created: 10/25/15
Exam 2 Study Guide Topic 3 Fatigue and Aging 1 Changes in postural control seen in older individuals 0 Increased postural sway 0 Delayed APAs 0 Switch from ankle to hip strategy 0 Greater coactivation of antagonist muscles 0 Higher variability stride to stride 2 Changes in fast movement production seen in older individuals 0 Slowness in movement initiation and execution 0 Longer deceleration 0 Higher reliance on visual feedback 0 More muscle cocontraction 3 Changes in hand function seen in older individuals 0 Motor 0 Loss of muscle force 0 Loss of voluntary force production 0 Poor multi digit coordination 0 Sensory 0 Decline in the number of receptors 0 Less discrimination 0 Larger decline in strength in intrinsic muscles belly in the hand balance forces than extrinsic muscles belly in forearm force producing muscles 4 Effects of training for improved function in older individuals 0 Helps to make individual produce higher forces 0 Lower antagonist cocontraction 0 Small changes in crosssectional area importance of neural adaptations Topic 4 Postural Control 1 Issues with maintaining bipedal posture 0 High center of mass 0 Multiple joints degrees of freedom problem 0 Small base of support area 2 Difference between COM and COP 0 COM center of mass meters 0 Point around which body s mass is equally balanced in all directions 0 Gives index of total body motion 0 Determines manner in which body responds to forces 0 From a horizontal standpoint the system is less stable if COM is near boundary BOS O From a vertical standpoint the system is less stable the higher the COM is 0 Can be altered by moving limbs 0 COP center of pressure meters 0 Location of the ground reaction force GRF vector 0 Modified by plantardorsi exion leaning or shifting weight from side to side 0 Location of COP modifies location of COM 3 Base of support BOS 0 Area enclosed by outermost edges of body in contact with supporting surface 0 The larger the BOS less likely the COM will move outside BOS and the more stable the system is 4 Contributions to postural control of sensory skeletal muscles and central nervous system Sensory Skeletal CNS Vestibular system located in Muscles of the upper and Stretch re ex the inner ear semicircular lower extremities canals otoliths maculaes Vision retina Trunk muscles Longloop re exes Proprioceptive system muscle Neck muscles Preprogrammed reactions type I and II golgitendon learned skills organ joint receptors Cutaneous receptors skin Synergistic action 0 Vestibular system 0 Semicircular canals three detect angular accelerations of head rotation exion nodding O Otoliths detect linear accelerations of the head horizontal accelerations thru body 0 Maculaes have hair that can bend in direction of accelerations of head and increasedecrease firing frequency in hair cells depending on acceleration 0 Proprioceptive system 0 Knowing what body and limbs are doing relative to environment and other limbs O Golgi tendon organ senses tension in muscles located where the tendons meet the muscles 5 Light touch study 0 Individuals in experiment that is testing balance 0 Showed amount of sway during test 0 Then allowed to repeat test again and this time allowed to touch nearby surface with no more than 1N of force 0 Provides reference point and helps tell how body is oriented in space which decreases sway 6 Mechanisms that help to maintain posture Mechanism Time Delay Comments APAs lt0 Based on prediction of perturbation Muscle elasticity 0 Monosynaptic re ex 30ms Poorly controlled Polysynaptic re ex 50ms Low gain Preprogrammed reactions 70ms Ankle vs hip strategy Voluntary action 150ms late 0 Cascade of events that happen once you start falling 0 Sequence of all of these things happening together to keep from fallling 0 Preprogrammed reactions 0 Involves brain so slower than re ex 0 Sometimes counterproductive can protect thing you re holding while sacrificing wellbeing 7 Anticipatory Postural Control 0 Generated prior to perturbation 0 Perturbation needs to be predictable 0 Perturbation needs to be associated with an action by the person not really ie firing a gun 0 Produce forcestorques acting against expected perturbation 0 Always suboptimal 0 Nervous system never 100 predicting does it to give time for voluntary actions to occur 0 However nervous system does scale adjustment to what is expected to occur 8 Ankle and Hip Strategy 0 Ankle strategy 0 Used to actively maintain balance for small amounts of sway 0 Only ankle movement occurs to maintain the COM over the BOS and is most commonly used when the perturbation is small and the support surface is firm 0 First strategy activated after a perturbation Muscle activation starts distally and moves proximally 0 Hip strategy 0 Reacts to larger faster perturbations and is used when one is standing on narrow or compliant surfaces 0 Both the ankle strategy and the hip strategy maintain stability within the stability limits 0 Muscle activation starts proximally and moves distally Tonic 5 Upper Motor Neurong 1 Arrangement of upper motor neurons in spinal cord 0 Upper motor neurons from cerebral cortex are arranged on lateral white matter of spinal cord and connect to lower motor neurons in lateral ventral horn 0 Upper motor neurons from brainstem are arranged in anteriormedial white matter of spinal cord and connect to lower motor neurons in the medialventral horn 2 Long vs short distance local circuit neurons 0 Local circuit neurons which lack long axons must exert all their effects in the local region of their cell bodies and dendrites located in brain areas served by the longaxoned principal neurons and act to affect the activity in these pathways 0 Perform integrative and modulating functions in local brain regions 0 Local circuit neurons with their short dendrites and small axons when present usually have small compact cell bodies 0 Principal neurons with their long axons usually have large cell bodies because the axon is dependent upon the cell body for metabolic energy and for the proteins that it needs to function and maintain itself 3 Different tracts originating from brain stem 0 Naming convention based off where they originate and where they end ex vestibulospinal tract start at vestibular nuclei and end at spinal cord 0 Colliculospinal tract 0 Eye gaze 0 Eye orientation 0 Vestibulopsinal tract 0 Medial I Axial muscles head and neck position I Input from the semicircular canals 0 Lateral I Limb muscles 0 Projections to cranial nerve O Vestibuloocular re ex maintenance of eye gaze with head movement eyes countermove in opposite direction of head so environment doesn t look like its moving with movement 0 Reticulospinal tract 0 Posture 0 Feed forward control APA happen so quickly nervous system doesn t register environment so time for sensory feedback happens in absence of sensory info governed in brain stem by superior colliculus O Respiratorycardiovascular Eye movement 0 Movement coordination works to stabilize body during rapid movements without thinking 0 Sleep 0 4 Anticipatory postural control 0 Reticular formation anticipates What level of instability Will occur and works to stabilize body against it 5 Cortical tracts 0 Corticobulbar tract 0 Cranial nerve reticular formation areas of the brain 0 Corticospinal tract 0 Lateral From motor cortex down stem crossover at medulla and continue down respective side direct projections distal limbs O Medialanterior don t crossover at medulla stay on same side connect to medial musculature and postural muscles 0 Ventral axial and postural muscles 6 Motor cortex activation 0 Cells fire and activate musculature 0 More cells used for fine motor control than postural muscles because high precision movements large amount of brain in control of these areas 7 Premotor cortex selection 0 Connection With premotor cortex 0 30 of axons in corticospinal tract 0 Lateral premotor cortex 0 Select movements for actions external cues 0 Change in planning of execution from external stimuli feedback 0 Medial premotor cortex 0 Initiate movements based on internal cues 0 Feed forward
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