audiovestibular system reflexes and EP

Question 1

two main auditory reflexes

Answer 1

startle and acoustic reflex

Question 2

startle reflex

Answer 2

the effect a loud sound has and how it causes a startle
-formerly used to test infants (moro reflex)
-basic startle reflex for adults

Question 3

startle reflex pathway

Answer 3

cochlea to CN 8 to cochlear nucleus (AVCN) to VNLL then to reticular pontine formation to medial longitudinal fasiculus out to spinal cord

Question 4

what happens with the startle reflex when it goes out to the spinal cord?

Answer 4

lower motor neurons are stimulated which allow for a quick, tense movement

Question 5

what is involved within the startle reflex

Answer 5

-cortical areas (A1) to receive the signal
-limbic system and ANS (autonomic nervous system) for emotions (fight or flight)
-IC and SC to help orient the head

Question 6

acoustic reflex

Answer 6

sound to one ear generates a reflex in both ears
-ipsilateral and contralateral reflex’s

Question 7

ipsilateral reflex pathway

Answer 7

3 arch : CN 8 to antero-ventral cochlear nuclei to facial motor nucleus to stapedial muscle
4 arch : nerve fibers to antero-ventral cochlear nucleis to medial superior olive to facial motor nuclei to stapedial muscle

Question 8

ipsilateral acoustic reflex threshold testing (ART)

Answer 8

playing a sound in one ear and testing the reflex in the same ear
-testing the health of the ipsi response

Question 9

contralateral reflex pathway

Answer 9

1st route : CN 8 to antero-central cochlear nuclei to medial supeior olive crossover to facial motor nucleus to stapedial muscle
2nd route : CN 8 to antero-central cochlear nucleus crossover to medial superior olive to facial motor nucleus to stapedial muscle

Question 10

contralateral acoustic reflex threshold testing (ART)

Answer 10

playing a sound in one ear and testing the reflex in the other ear
-testing to see if sound can travel over

Question 11

reflex decay

Answer 11

play loud sound above reflex threshold for 10 seconds
-tells us about the integrity of CN 8 fibers to see if they can hold the reflex for 10 seconds

Question 12

recruitment

Answer 12

abnormal growth of loudness
-can occur as a result from a certain HL where outer hair cells are damaged or lost and so higher frequencies will still sound loud but those lower ones are affected

Question 13

evoked potential

Answer 13

(electrical response of the brain to a sensory stimulus)
ability to measure the bioelectrical activity of the cochlea, peripheral nerves and central nervous system nuclei and neurons

Question 14

bioelectric energy

Answer 14

neurons create bioelectric energy
-the current in the extracellular space creates an electrical or potential field
-this field has negative polarity at one end and a positive polarity at the other end

Question 15

EEG montage

Answer 15

where we are playing electrodes and mapping them out
-the 10-20 system EEG montage

Question 16

within the EEG montage, even refers to what side? odd?

Answer 16

even - right
odd - left

Question 17

Fpz

Answer 17

prefrontal center

Question 18

Fz

Answer 18

high forehead

Question 19

Cz

Answer 19

central vertex/midline

Question 20

A

Answer 20

auditory

Question 21

what does electrocohleography (ECochG) measure

Answer 21

cochlear potentials

Question 22

process of ECochG

Answer 22

sound (stimulus) is played through insert earphones, headphones, a speaker or bone ossilator, voltages are measured, EEG are averaged, remaining waves measured in relation to times based on start of stimulus

Question 23

what are the two cochlear potentials

Answer 23

cochlear microphonic (CM) and summating potential (SP)

Question 24

auditory brainstem response

Answer 24

another test that involves the CANS
-measures absolute latency, interpeak latency, amplitudes/amplitude ration, and neural generators
-playing a sound and measuring voltage changes

Question 25

absolute latency

Answer 25

where did it occur
-time

Question 26

interpeak latency

Answer 26

distance between the two waves
-time

Question 27

amplitude

Answer 27

peak of individual wave

Question 28

amplitude ratio

Answer 28

comparing amplitude peaks to each other

Question 29

neural generators

Answer 29

later waves are complex with multiple neural generators contributing to each other

Question 30

wave numbers and their perceived location within an ABR

Answer 30

1 - distal CN 8
2 - proximal CN 8
3 - cochlear nucleus
4 - SOC leading to LL
5 - LL leading to IC