Lecture 17 - Spinal circuits

Question 1

what is decussation regarding the descending pathways?

Answer 1

the right and left corticospinal tracts cross over at the medulla

Question 2

true or false, the motor system is hierarchical?

Answer 2

true

Question 3

locomotion comes from what type of generators, what type of feeback and what type of input?

Answer 3

central pattern, sensory, descending

Question 4

which 2 genes control the development of dorsal/posterior areas in spinal circuit development?

Answer 4

wnt, bmp

Question 5

which gene controls the development of ventral/anterior areas in spinal circuit development?

Answer 5

shh

Question 6

in early development which 2 things are active before the sensory reflex is complete?

Answer 6

motorneurons and central pattern generators

Question 7

which type of interneurons do renshaw cells inhibit for extension?

Answer 7

1a

Question 8

VI interneurons use which 2 neurotransmitters to allow alternating activity between flexor and extensor motoneurons?

Answer 8

GABA and gylcine

Question 9

what do gamma sensory fibres detect?

Answer 9

touch, pain, heat, vibration

Question 10

what do C sensory fibres detect?

Answer 10

pain, heat

Question 11

which 3 types of sensory fibres are heavily myelinated and which are lightly myelinated?

Answer 11

alpha, beta, delta heavily, gamma lightly

Question 12

the stretch reflex is …..synaptic but the flexor reflex is …..synaptic

Answer 12

mono, multi

Question 13

give an example of the flexor and crossed extensor reflex?

Answer 13

stepping on something sharp and planting the other foot on the ground to move the harmed foot up and away promoting extension

Question 14

in the flexor and crossed extensor reflex, what inhibits flexor motion with interneurons?

Answer 14

CPGs

Question 15

which type of neurons work the arms and the legs at the same time? which 2 regions of the spinal cord do they communicate between?

Answer 15

long propriospinal neurons, cervical and lumbar

Question 16

in the transcortical (slow) reflex pathways, axons ascend up through which two structures? where do they go in the brain after? which tract do they signal back down through?

Answer 16

up through nucleus gracilis and nucleus cuneatus to thalamus and somatosensory cortex/motor cortex, back down through spinothalamic tract

Question 17

ascending pathways in the 3-spinocerebellar tracts carry impulses to a ……. level

Answer 17

subconscious

Question 18

clarke’s column is a group of large cells which recieves inputs from which group afferents?

Answer 18

1a

Question 19

the activation of what in the spinal cord disasppears as what is established in the stepping reflex in newborns?

Answer 19

corticospinal influence

Question 20

which tract controls the voluntary control of distal musculature? which controls proximal musculature?

Answer 20

lateral corticospinal, anterior corticospinal