lecture 5 electrical potentials 2

Question 1

Of the 3 ocular electrical recordings, (EOG, ERG, VEP) which measure retinal activity alone and which measure brain activity with regards to retinal input?

Answer 1

EOG and ERG solely respond to what the retina is doing. VEP measures what the brain is doing in response to the retinal input.

Question 2

With VEP we are analyzing the ____ of ____

Answer 2

latency, P100

Question 3

true or false: VEP can be successfully performed on a patient under anesthesia

Answer 3

false-patient must be conscious.

Question 4

Name the procedure:

a 40HZ flicker gives 4 peaks, a 50HZ flicker gives 5 peaks, a 60hz flicker gives 6 peaks

Answer 4

this is called steady-state VEP. You should notice that when you increase the flicker, the peak numbers should increase accordingly.

Question 5

a visual fields test will provide what kind of defect information?

a) layers (photoreceptors vs. bipolar cells, etc)
b) zones (central vs peripheral)
c) subsystems (retina vs brain)

Answer 5

b) zones

Question 6

a standard ERG,EOG,VEP test will provide what kind of defect information?

a) layers (photoreceptors vs. bipolar cells, etc)
b) zones (central vs peripheral)
c) subsystems (retina vs brain)

Answer 6

a) layers and c) subsystems

Question 7

an mf ERG, VEP test will provide what kind of defect information?

a) layers (photoreceptors vs. bipolar cells, etc)
b) zones (central vs peripheral)
c) subsystems (retina vs brain)

Answer 7

a) layers and b) zones

Question 8

retinal disease _____ mfVEP latency

a) increases
b) decreases

Answer 8

a) increases

Question 9

can a neutral density filter mimic the effects of a retinal disease?

Answer 9

yes, a neutral density filter reduces retinal illuminance, which increases the latency of the VEP, much like a retinal disease.

Question 10

does a neutral density filter decrease VEP amplitude?

Answer 10

only minimally

Question 11

A -3 log ND filter would make a person virtually ____

Answer 11

blind

Question 12

A -2 log ND filter combined with a -1 log ND filter would become a ___ log ND filter

Answer 12

-3, they are additive

Question 13

In the VEP waveform, the tall peak in the middle is called ____ and the 2 on the sides are ____ and ____

Answer 13

P100, N75, N135

Question 14

True or False: In the VEP waveform, the P100 peak is an upright peak and the N75 and N135 peaks are downward pointing peaks.

Answer 14

True-P=positive and N=negative