EEG Evoked Potentials 5

Question 1

Which cognitive evoked potential component is considered the gold standard for assessing auditory discrimination and working memory?

Accepted Answer

P300 (P3b)

Answer

The P300 (P3b) is an endogenous, task-related component elicited by target detection in an oddball paradigm, widely used to assess cognitive processing speed and memory.

Question 2

The N400 event-related potential is characteristically elicited by:

Accepted Answer

Semantically incongruent words in a sentence

Answer

The N400 is a negative deflection peaking ~400 ms that reflects semantic mismatch processing, elicited when a word violates the expected meaning of a sentence.

Question 3

Cortical somatosensory evoked potentials recorded over the scalp after median nerve stimulation include which early obligate component?

Accepted Answer

N20

Answer

N20 is the first cortical (primary somatosensory cortex) component of the median nerve SSEP, typically appearing ~20 ms post-stimulus in adults.

Question 4

Mismatch negativity (MMN) is unique among auditory evoked potentials because it:

Accepted Answer

Can be recorded during sleep or in unresponsive patients

Answer

MMN is a pre-attentive, automatic response to auditory change that can be recorded without voluntary attention, making it useful for assessing auditory discrimination in comatose patients.

Question 5

In VEP testing, what is the main reason each eye is tested separately with the other eye patched?

Accepted Answer

To isolate each optic nerve's conduction independently

Answer

Monocular testing isolates the optic nerve pathway anterior to the chiasm, allowing detection of unilateral demyelination or compressive lesions of a single optic nerve.

EEG - Electroencephalography Practice Test

EEG - Electroencephalography Practice Test

EEG Evoked Potentials 5