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Other VEPs
Other visual evoked potential applications
| Question | Answer |
|---|---|
| The VEP generated by onset and offset of a pattern resembles a typical pattern reversal VEP with pattern __ (onset/offset) | offset |
| Four conditions in which VEP to onset and offset of a pattern have been reported to be abnormal | hemispherectomy, MS, phenylketonnuria, schizophrenia |
| __ VEPs are those produced by pattern reversal atimuli at rates faster than those used by normal pattern reversal VEPs; they are essentially the superimposition of transient VEPs | rhythmic |
| Rhythmic VEPs begin at rates of __ per second and are greatest at rates of __ - __ per second; at higher rates, larger check sizes are more effective | 4, 6, 8 |
| Repetitive flash stimuli result in a rhythmical wave; at rates above __ per second, there is an increasing phase lag proportion to the rate | 10 |
| The highest rate at which a steady state VEP can be distinguished is called the _________; it varies inversely with age | critical frequency of photic driving |
| The mean critical frequency of photic driving for patients aged 20 - 30 | 72 |
| The mean critical frequency of photic driving for patients aged 30-60 | 68 |
| The mean critical frequency of photic driving for patients aged > 60 | 60 |
| __ are alternating light and dark stripes with midlines of maximal and minimal luminance and gradual transitions between the maxima | Sine-wave gratings |
| For transient VEPs to sine wave stimuli, the size of the pattern elements is maeasured in units as __ per __ | cycles per degree of visual angle |
| With a sine wave grating pattern of < __ the response for sine wave grating pattern resembles that of a pattern reversal VEP | 1 cycle per degree |
| Sine wave grating patterns > ___ c/d consist of two early and two late negative-positive peaks whose latency and amplitude vary with spatial frequency and cotnrast depth | 1 |
| MS leads to a __ latency in the majority of patients with VEPS to sine wave stimuli | increased |
| Sine wave stimuli may add __ (more/less) diagnostic sensitivity to pattern reversal VEPs | more |
| __ are alternating light and dark stripes with midlines of maximal and minimal luminance and gradual transitions between the maxima | Sine-wave gratings |
| For transient VEPs to sine wave stimuli, the size of the pattern elements is maeasured in units as __ per __ | cycles per degree of visual angle |
| With a sine wave grating pattern of < __ the response for sine wave grating pattern resembles that of a pattern reversal VEP | 1 cycle per degree |
| Sine wave grating patterns > ___ c/d consist of two early and two late negative-positive peaks whose latency and amplitude vary with spatial frequency and cotnrast depth | 1 |
| MS leads to a __ latency in the majority of patients with VEPS to sine wave stimuli | increased |
| Sine wave stimuli may add __ (more/less) diagnostic sensitivity to pattern reversal VEPs | more |
| __ VEPS refer to VEPs that use a rhythm whose amplitude varies with spatial frequency and reaches a maximum at about a value that corresponds to the most effective checkerboard pattern | steady state sine wave grating |
| The measurement of subjective contrast threshold at different spatial frequencies | visuogram |
| Steady state VEPS to __ are used to plot spatial tuning curves -- i.e., plots of the ability to detect contrast | sine wave grating |
| ____ consist of light and dark stripes of equal width with sharp borders between them | bar gratings |
| Maturation of the bar grating VEP occurs between __ and __ months of age | 4, 6 |
| The __ is elicited by recording using electrodes on the cornea, sclera or near the eye | ERG |
| The two types of ERG | patterned ERG, flash ERG |
| THe two waves of the ERG | a, b |
| The a wave of the ERG to diffuse light is probably generated by __ | photoreceptors |
| The b wave of the ERG to diffuse light is probably generated by __ | glial Muller cells |
| The a wave of the ERG to diffuse light is cornea __ (negative/positive) | negative |
| The b wave is cornea __ (negative/positive) | positive |
| The ganglion cells of the retina generate the __ wave of the ERG to diffuse light (a/b/neither) | neither |
| The __ wave of the ERG to diffuse light is generated by photoreceptors | a |
| The __ wave of the ERG to diffuse light is generated by glial Muller cells | b |
| Simultaneous recording of patterned __ with VEP can be used to distnguish retinal from central disorders | ERG |
Created by:
schmittse
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