UMass Amherst KIN 460 - 06-Spinal cord and PNS- reflex circuits and CPG (28 pages)

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06-Spinal cord and PNS- reflex circuits and CPG



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06-Spinal cord and PNS- reflex circuits and CPG

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Pages:
28
School:
University of Massachusetts Amherst
Course:
Kin 460 - Motor Control
Unformatted text preview:

Review Neurons in the spinal cord Ventral motor neurons dorsal sensory neurons Local circuit neurons long and short distance Types of motor units and force production fatigue 3 types I IIa and IIb Force Regulation Motor unit recruitment size principle Frequency of APs synchronization Training and motor unit types animal research Spinal cord reflex circuits What is the neural circuitry for basic reflexes What is the function of the muscle spindle What is the function of the Golgi tendon organ GTO What is a Central Pattern Generator CPG Lower motor neuron damage Overall organization of neural structures that control movement Spinal cord reflex circuits What is the neural circuitry for basic reflexes What is the function of the muscle spindle What is the function of the Golgi tendon organ GTO What is a Central Pattern Generator CPG Lower motor neuron damage Monosynaptic reflex arc A simple reflex circuit the knee jerk response A simple reflex circuit the knee jerk response Intracellularly recorded responses underlying the myotatic reflex Soleus muscle in the cat Overview motor and sensory neurons alpha motor neuron innnervates muscle fibers gamma Motor neuron innervates muscle spindle fibers Ia sensory afferent from muscle spindle Ib sensory afferent from golgi tendon organ GTO Spinal cord reflex circuits What is the neural circuitry for basic reflexes What is the function of the muscle spindle What is the function of the Golgi tendon organ GTO What is a Central Pattern Generator CPG Lower motor neuron damage Muscle spindle Gamma motor neurons regulate spindle length prevent slack A simple reflex circuit the knee jerk response Gamma motorneuron Function of gamma motor neurons Gamma motor neuron activity Gamma motor neuron activity gain or bias Gain refers to the amount of muscle force generated in response to a given stretch of the intrafusal fibers during Consistent level of active smaller neuron smaller excitatory threshold High gain small stretch greater in muscle force motor neuron recruitment and firing rate Low gain greater stretch needed for similar amount of muscle force Animation of reflex arc Servo hypothesis Spinal cord reflex circuits What is the neural circuitry for basic reflexes What is the function of the muscle spindle Next class What is the function of the Golgi tendon organ GTO What is a Central Pattern Generator CPG Lower motor neuron damage Golgi tendon organ GTO Negative feedback regulation of muscle tension by Golgi tendon organs GTO Sensitive to muscle tension from muscle contraction but not from muscle stretch Maintains steady force level fatigue Inhibits large forces Spinal cord circuitry responsible for the flexion crossed extension reflex Flexion reflex Crossed extensor reflex Overview What is the neural circuitry for basic reflexes What is the function of the muscle spindle What is the function of the Golgi tendon organ GTO What is a Central Pattern Generator CPG Lower motor neuron damage Figure 16 15 Central pattern generators in terrestrial mammals Part 3 https youtu be wPiLLplofYw Spinal Pattern Generators CPG Neuronal spinal networks capable of generating rhythmic motor activity in the absence of rhythmic input from peripheral receptors Main feature Many forms of locomotion Rhythmic and alternating movements appears to be stereotyped repeated action Allows automatic control at lower levels of the nervous system Still requires continuous and subtable modifications to adapt to different environments From sensory information From other regions of the CNS Do humans have CPGs Indirect support Evidence of CPGs across number of species vertebrate and invertebrate Some evidence of rhythmic lower limb movements after complete SCI in humans Evidence of rhythmic stepping movements very early in human development also in anencephaly Spinal Cord rehab Spinal cord retraining based on current knowledge of central pattern generators and reflexes Injecting L Dopa in spinal cord alternating flexion extension movements cat mouse Overview What is the neural circuitry for basic reflexes What is the function of the muscle spindle What is the function of the Golgi tendon organ GTO What is a Central Pattern Generator CPG Lower motor neuron damage Lower motor neuron syndrome muscle fibers motor nerve fiber Cardinal signs of lower motor neuron syndrome 1 Paralysis loss of movement Paresis weakness 2 Loss of reflexes 3 Loss of muscle tone 4 Atrophy 5 Degeneration MS ALS ALS or Lou Gehrig s disease Degeneration of a motor neurons spinal cord genetic mutations


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