Lecture 13 - Somatosensory Evoked Reflexes

Question 1

What is disynaptic connectivity?

Answer 1

2 synapses

Question 2

What is a convergent pathway?

Answer 2

Multiple neurons to one neuron (large to small population)

Question 3

What is a divergent pathway?

Answer 3

1 neuron to multiple neurons (small to large population)

Question 4

What is it called when there are more than 2 synapses?

Answer 4

Polysynaptic

Question 5

What is reciprocal inhibition?

Answer 5

contraction of agonist muscle with inhibition of antagonist muscle

Question 6

What is tonic excitatory input?

Answer 6

Another input, could be a sensory input or a descending input

Question 7

What is flexion-crossed extension relex (for example when stepping on a nail)?

Answer 7

Retracting injured leg (hip flexor + hamstring contracts), as a result your other leg compensates and you extend quads and glutes and press down into the ground harder with your other leg so you don’t fall over

Question 8

What is a positive Babinski sign?

Answer 8

When a blunt probe is stroked across the plantor surface of the foot toes curl back (we went them to curl forward), this could be a sign of spinal cord injury

Question 9

What is the golgi tendon organ autogenic inhibition reflex?

Answer 9

when active force production gets to high, muscle inhibition will occur to prevent ruptured tendons

Question 10

Can we overcome the GTO autogenic inhibition reflex?

Answer 10

Yes, with training GTO will desensitize

Question 11

What does the renshaw cell manage?

Answer 11

upper firing rate of MNs

Question 12

How does the renshaw cell manage the upper firing rate of a MN?

Answer 12

A negative feedback loop or recurrent inhibition. It gets activated by a branch of the motor neuron and in turn inhibits that very samWhye MN

Question 13

Why are MNs known as the final common path?

Answer 13

Because they receive a vast array of synaptic inputs, and if AP threshold is reach they fire and produce movement