Neuro Ch 7

  1. skeletal muscle
    • comprises a collection of muscle fibres arranged in fascicles 
    • each fibre has myofibril, each myofibril have sarcomeres

    some work as opposing pairs (one contract, other relax). Flexors vs extenders
  2. proprioceptive organs
    sense contraction and load
  3. muscle spindles
    somatosensory receptors embedded in the body of muscles; sense the length of muscles and prevent them from being overstretched
  4. golgi tendon organs
    somatosensory receptors embedded in tendons, sense changes in muscle tension and prevent excessive tension from damaging the muscle
  5. slow twich fibers
    • specialised for endurance
    • type 1
  6. fast twitch fibers
    • specialised for speed and power
    • type 2
  7. neuromuscular junction
    place where endplates of muscle fibres are contracted by motor neurons
  8. miniature end plate potential
    • when action potentials in motor neuron will release acetylcholine into the synapse
    • summation of enough miniature endplate potentials will cause muscles contraction
  9. botox aka botulinum toxin
    paralyses muslce by preventing vesicles filled with ACh from fusing with the presynaptic membrane, so motor neurons can't activate muscles
  10. lower motor neurons
    originate in the ventral horn of the spinal chord
  11. alpha motor neurons
    stimulate contractions in skeletal muscle to cause movements of the body
  12. gamma motor neuron
    maintain tension in muscle spindles
  13. motor unit
    • consist of a single alpha motor neuron and all the muscle fibres that innervate
    • different motor = different number of muscle fibres, more MF are innervated, stronger muscle contraction
  14. motor pool
    • consist of all the motor units that work together within a single muscle 
    • each pool can produce variety of contraction forces by recruiting different motor units, recruited from smallest to largest
    • smallest = weak contraction and precise control 
    • largest = strong contractions and courser movement
  15. disease of motor neurons
    • polio - virus that attacks motor neurons in the spinal cord causing flaccid paralysis 
    • west nile virus - damage ventral horn of the spinal cord and can sometimes cause severe, long lasting muscle weakness
  16. spinal reflexes
    automatic movements mediated by the spinal cord (don't require input from the brain)patellar tendon reflex
  17. why do we need inhibitory feedback?
    • inhibitory mechanism prevent severe muscle spasms and injuries (both extensors and flexors activated at the same time)
    • tetanus and strychnine poisoning - causes severe muscle spasms all over the body (death by asphyxiation)
  18. corticospinal tract
    • most important for fine motor control in humans 
    • from the brain
  19. upper motor neurons
    from primary motor cortex, can modulate lower motor neurons in the spinal chord
  20. motor homunculus
    • name of somatotopic map of the body in the primary motor cortex
    • electric simulation of different parts of motor cortex elicit movement in different parts of the body
  21. premotor cortex
    other motor areas exists important for guiding more complex movements, including voluntary eye movement
  22. neural coding of movements
    • upper motor neurons (originate in PMC) connect to lower motor neurons (originate in SC) at all levels of the spinal cord
    • also connect to interneurons in the spinal chord, enabling modulation of spinal reflexes
  23. population coding
    • upper motor nueronce influence movement via PC. 
    • Each neuron has coarse directionl preference and the summation of activity across the population determines the movement. 
    • high firing for fowards and left movement, no firing for backward and right movements
  24. strategic guidance of movements
    • hierarchy of control 
    • primary motor cortex: simple movements
    • premotor cortex: complex movements, actions 
    • dorsolateral/ventrolateral prefrontal cortex: cognition, rule-guided behaviour
    • frontopolar cortex: long term goals, multitasking
  25. mirror neurons
    • premotor neurons that fire when an animal performs a particular action of when the animal witnesses someone else perform a similar action
    • fire in response to goal-directed actions no just any movement
    • respond even when part of motion is not seen, or when a consequence of the movement is heard
  26. cerebellum
    critical for many forms of motor control, including smoothness and accuracy of motor trajectories, and correction of movements
  27. non motor functions of the cerebellum
    • projects to the frontal cortical regions involved in cognition, emotion, motivation, and judgement 
    • cognitive affective syndrome - when damaged cerebellum, leads to impairments in cognitive and emotional functions
  28. basal ganglia
    • Grey matter structures buried deep in the brain 
    • works closely with the cortex to coordinate movement including intitating and maintaininig cortical activity
    • every cortical area except low level sensory cortices is served by loop circuits through the basal ganglia
  29. Huntington's disease
    • genetic disorder in which abnormal huntingtin proteins cause the caudate and putamen to degenerate
    • initially affects the inhibitory circuitry of the basal ganglia leading to chorea
  30. Parkinson's disease
    parkinson's disease: result of degeneration of dopinergetic neurons in the substantia nigra
  31. lateral and medial motor systems
    motor regions in lateral areas are primarily influenced by external stimuli motor regions in medial areas are primarily influenced by internal states and motivations
  32. damage to lateral and medial motor systems
    • damage to the medial motor: impairs internally generated movements but leaves externally cued movements intact 
    • damage to lateral motor areas impairs externally cued movements but leaves internally generated movements in tact
Card Set
Neuro Ch 7
cognitive neuroscience