The Motor Basis Of Animal Behaviour

Question 1

Motor neurons mediate control of movement

Question 2

Invertebrates have simple neural circuits of single neurons e.g. the reflex startle response

Question 3

Vertebrates Have Two Spinal Reflexes…

Answer 3

1) Stretch reflex
2) Flexion Reflex

Question 4

Muscle Spindle

Answer 4

• A type of mechanoreceptor (Proprioceptor - provides positional information of the body)
• Monitors the length of the muscle

Question 5

Muscle Spindle Composed Of….

Answer 5

• Intrafusal fibres within a capsule
• 1a afferent: largest and fastest type of sensory neuron
• Gamma motor neuron

Question 6

Muscle Spindle (contracting)

Answer 6

• When the working (normal) extrafusal muscle fibers contract (shorten) or relax (lengthen) so too do the intrafusal fibers
• Innervated by sensory neuron that contains mechanoreceptors

Question 7

Stretch reflex: A monosynaptic reflex arc

Question 8

Extensor Muscle

Answer 8

• when contracted, extends limb (e.g. Quad/ triceps)

Question 9

Flexor Muscle

Answer 9

• when contracted, shortens limb (e.g. hamstrings/biceps)

Question 10

Flexion Reflex: A Polysynaptic Reflex Arc -

Answer 10

• involves interneurons
• Acts on multiple muscle groups in both legs, to compensate for change in weight

Question 11

Flexion reflex: A polysynaptic reflex arc

Answer 11

• CNS estimates amount of force necessary
  – Commands lower motor neurons to generate force
• Stretch reflex mediates load compensation

Question 12

The central-control hypothesis

Question 13

Central Pattern Generator

Answer 13

• A neural circuit (or single neuron) that generates a behaviourally significant pattern of motor output in space and time without requiring temporally patterned sensory input