PTP 512 Neuroscience in Physical Therapy Motor Control: Action System. Min H. Huang, PT, PhD, NCS Reading Assignments S & W: 478-480, 493-494, 69-74, 75-76, 76-77, 78-81 L-E: 187-189, 201-204, 221-222. Objectives. Describe and demonstrate spinal modulated reflexes
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PTP 512Neuroscience in Physical TherapyMotor Control: Action System
Min H. Huang, PT, PhD, NCS
S & W: 478-480, 493-494, 69-74, 75-76, 76-77, 78-81
L-E: 187-189, 201-204, 221-222
Blumefeld, 2010; Lundy, 2007
With conscious intention to move
The three traces in each panel are, from top to bottom, rectified biceps, and triceps EMG, angular position.
Click to view animationFigure 1.4. Byrne, 1997.
Click to view animation. Figure 1.5. Byrne, 1997.
Click to view animation. Figure 1.6. Byrne, 1997.
Stimulus excites muscle spindle which sends signals via Ia afferents to α motor neuron
Muscle spindle information also goes to supraspinal regions via a long-loop reflex pathway, i.e. transcortical reflex, or functional stretch reflex.
Click to view abnormal DTR
For example, perturbation of one arm causes different responses in the contralateral arm, depending on the task.
Task instructions and environmental stiffness modify stretch reflex
PTB: rapid stretches to biceps
SLR: short-latency stretch reflex (monosynaptic)
LLR: long-latency stretch reflex (polysynaptic and transcortical)
Noxious stimulus to skin causes protective withdrawal of limb through
Typically occurs in conjunction with flexor withdrawal. Noxious stimulus causes contralateral
Contraction or stretch of muscle pulls on the Golgi tendon organ (GTO). GTO sends signal to α motor neuron via Ib afferents and causes
Finger flexor (Hoffman)
Tap or flick the terminal phalanx of the 3rd or 4th digit
flexion of terminal phalanx of thumb
UE equivalent of Babinski
View Hoffman Reflex http://neuroexam.com/neuroexam/content.php?p=33
View Babinski Reflex http://neuroexam.com/neuroexam/content.php?p=32
Evarts’ study (1968)
monkeys made wrist flexion/extension
View animationFigure 3.7
Vectors show firing of neurons to movements in different directions ( indicates max response)
Monkeys moved lever toward light
Hand velocity during a reaching task.
View animation Figure 3.2
View animation Figure 3.10 http://neuroscience.uth.tmc.edu/s3/chapter03.htm
Mirror Neuron. NOVA Science Now. http://www.pbs.org/wgbh/nova/body/mirror-neurons.html
Mirror Neuron. Human Spark. http://www.pbs.org/wnet/humanspark/video/web-exclusive-video-mirror-neurons/404/
View animation Figure 3.12
View animation Figure 3.13.
Fine tuning of movement in feedback control: cerebellum compare “efferent copy” of motor program with incoming sensory feedback to correct for deviations from the intended movement outcome.
Motor learning and feedforward control: cerebellum evaluates sensory information and movement errors to modify the strength of synaptic connections in cerebellar cortex. As a result, future movements in a similar context will be modified.
The University of Utah 2001
TURNS DOWN motor activity
Facilitate or select appropriate movement
Inhibit unwanted or inappropriate movement
Huntington’s disease Macrographia