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Questions and Answers
Which category of auditory evoked potentials (AEPs) includes both the N1 – P2 complex and P300?
Which category of auditory evoked potentials (AEPs) includes both the N1 – P2 complex and P300?
What is primarily reflected by the latency epoch of an AEP?
What is primarily reflected by the latency epoch of an AEP?
Which potential is categorized as transient?
Which potential is categorized as transient?
Which response relies predominantly on the physical features of the stimulus?
Which response relies predominantly on the physical features of the stimulus?
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What is the origin of the first peak in an Auditory Brainstem Response (ABR)?
What is the origin of the first peak in an Auditory Brainstem Response (ABR)?
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Which of the following is an example of a sustained potential?
Which of the following is an example of a sustained potential?
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What characteristic distinguishes endogenous potentials from exogenous potentials?
What characteristic distinguishes endogenous potentials from exogenous potentials?
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Which auditory evoked potential is typically used in an oddball paradigm?
Which auditory evoked potential is typically used in an oddball paradigm?
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What term is used to refer to the electrical responses of the nervous system elicited by a stimulus?
What term is used to refer to the electrical responses of the nervous system elicited by a stimulus?
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Which of the following is NOT an advantage of using Auditory Evoked Potentials (AEPs)?
Which of the following is NOT an advantage of using Auditory Evoked Potentials (AEPs)?
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What is the latency epoch for Early or Short Latency Responses (SLR)?
What is the latency epoch for Early or Short Latency Responses (SLR)?
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Which component is most prominent in the Middle Latency Response (MLR)?
Which component is most prominent in the Middle Latency Response (MLR)?
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How are Auditory Evoked Potentials (AEPs) primarily classified?
How are Auditory Evoked Potentials (AEPs) primarily classified?
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What is the range of latency for Long Latency Responses (LLR)?
What is the range of latency for Long Latency Responses (LLR)?
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Which auditory evoked potential occurs within the 0-10 ms range?
Which auditory evoked potential occurs within the 0-10 ms range?
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Which of the following classifications of AEPs is characterized by components generated beyond 80 ms post stimulus?
Which of the following classifications of AEPs is characterized by components generated beyond 80 ms post stimulus?
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Which electrode positions are used for single channel recordings in the 10-20 system?
Which electrode positions are used for single channel recordings in the 10-20 system?
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What is the primary function of preamplifiers in the AEP recording system?
What is the primary function of preamplifiers in the AEP recording system?
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What is indicated by excessive activity in the waveform display during AEP recording?
What is indicated by excessive activity in the waveform display during AEP recording?
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How much amplification is typically provided by the accompanying amplifier and preamplifier for AEP signals?
How much amplification is typically provided by the accompanying amplifier and preamplifier for AEP signals?
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What role does the ground electrode play during AEP recordings?
What role does the ground electrode play during AEP recordings?
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What characterizes near field recordings in AEPs?
What characterizes near field recordings in AEPs?
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Which of the following describes far field recordings in AEPs?
Which of the following describes far field recordings in AEPs?
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What is the primary purpose of the stimulus generator in AEP instrumentation?
What is the primary purpose of the stimulus generator in AEP instrumentation?
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What is a key feature of the clicks used in AEP testing?
What is a key feature of the clicks used in AEP testing?
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What equipment is notably recommended for acquiring AEPs?
What equipment is notably recommended for acquiring AEPs?
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What essentially constitutes the recording system in AEP instrumentation?
What essentially constitutes the recording system in AEP instrumentation?
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What is a significant challenge when using AEPs to estimate hearing sensitivity?
What is a significant challenge when using AEPs to estimate hearing sensitivity?
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Which of the following components is NOT typically part of AEP instrumentation?
Which of the following components is NOT typically part of AEP instrumentation?
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What is one advantage of insert receivers in audiometric tests?
What is one advantage of insert receivers in audiometric tests?
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Which is a common disadvantage of supra aural earphones?
Which is a common disadvantage of supra aural earphones?
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What purpose does a trigger serve in auditory evoked potentials?
What purpose does a trigger serve in auditory evoked potentials?
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What is one of the primary uses of bone vibrators in audiometric testing?
What is one of the primary uses of bone vibrators in audiometric testing?
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Which of the following is true regarding electrode placement for AEP recordings?
Which of the following is true regarding electrode placement for AEP recordings?
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Which of the following characteristics is more reliable for insert receivers compared to supra aural earphones?
Which of the following characteristics is more reliable for insert receivers compared to supra aural earphones?
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Why is it important to ensure precise electrode placement in AEP recordings?
Why is it important to ensure precise electrode placement in AEP recordings?
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What major disadvantage do insert receivers have compared to supra aural earphones?
What major disadvantage do insert receivers have compared to supra aural earphones?
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Study Notes
Auditory Evoked Potentials (AEPs)
- AEPs are electrical signals produced by the nervous system in response to a stimulus, typically sound.
- The signals are picked up by electrodes placed on the head and displayed on a recording device (e.g., EEG).
- A change in nervous system activity, caused by the stimulus, results in changes in the electrical signals detected by the electrodes.
- These responses to a stimulus are called evoked potentials.
- When the stimulus is sound, they're called Auditory Evoked Potentials (AEPs).
Advantages of AEPs
- Used to evaluate the integrity of the auditory system.
- Used to gather information about hearing.
- Generally non-invasive, measured externally using electrodes on the skin.
Classification of AEPs
- Classification approaches vary but aren't standardized.
- AEPs are generally categorized based on these aspects:
- Latency epochs (time from stimulus onset)
- Anatomic origins (brainstem or cortical)
- Stimulus-response relationships (transient or sustained, endogenous or exogenous)
- Electrode placement (near-field or far-field)
AEPs based on Latency Epoch
- Latency epoch is the time domain within which a response occurs after stimulus onset.
- AEPs are divided into three categories:
- Early/Short Latency Responses (SLRs): Occur within 10-15 milliseconds after stimulus onset. Examples include ECochG, ABR, SN10, and FFR.
- Middle Latency Responses (MLRs): Occur between 10-50 milliseconds after stimulus onset; prominent feature is 40Hz steady-state potential.
- Long Latency Responses (LLRs): Occur beyond 50-80 milliseconds after stimulus onset, often referred to as slow or late responses; examples include N1-P2 complex and P300.
AEPs based on Anatomic Origin
- AEPs are categorized as either brainstem or cortical based on their origin.
- Short latency responses originate in the brainstem
- Long latency responses originate in the cortex
- Note that some responses, like the ABR's initial peak, originated from structures not consistently categorized as brainstem.
AEPs Based on Stimulus-Response Relationship
- AEPs are further categorized by whether their responses are:
- Transient or Sustained: based on the rise and fall time/pattern of the stimulus and response
- Endogenous or Exogenous: Exogenous responses are influenced by the physical characteristics of the stimulus. Endogenous responses aren't dependent on the stimulus's physical characteristics, but rather the patient's perception and arousal of that stimulus.
AEPs based on Electrode Placement
- AEP classification is also based on the location of recording electrodes relative to the site of the response generators.
- Two categories exist:
- Near-field recordings: Obtained when electrodes are placed near or on the neural generators. Slight changes in electrode placement significantly affect resultant wave morphology. Example: intra-operative recordings.
- Far-field recordings: Large distance between electrodes and generators. Site location has less of an impact on resulting morphology. Examples common scalp-level AEPs (ABR, MLR, LLR, etc.).
Instrumentation of AEPS
- Sophisticated computer-based systems are used for clinical AEP recordings.
- AEPs use a "stimulus system" and a "recording system."
- The stimulus system includes:
- Stimulus generator (clicks, tones)
- Attenuator (control stimulus intensity)
- Transducers (earphones, bone vibrators)
- The recording system includes:
- Electrodes (surface electrodes on scalp)
- Amplifiers (boost signal strength)
- Filters (remove unwanted noise)
- Averager (reduce background noise)
- Display unit (waveform visualization)
- Response processing unit (processing and saving the data)
Transducers in AEPs
- Earphones: Insert earphones (ER-3A) are often used due to reduced stimulus artifacts and better isolation of the signal, despite the potential for aural discomfort and risk of canal collapse. Supra-aural and bone conduction transducers are also used.
Triggering in AEPS
- A trigger pulse triggers the recording system to begin recording at the stimulus onset.
- It is used to isolate the signal from background noise.
Electrodes in AEPS
- Electrodes are placed on the scalp to capture the AEP signal.
- Common montages used include two or four electrodes.
- Specific electrode placements and configurations are important for properly capturing and interpreting the AEP signal.
Amplifiers and Preamplifiers, Display and Print, AEP
- Preamplifiers increase the strength of the evoked signal, necessary to overcome background noise.
- These waveforms can be viewed or averaged; artifacts are typically identifiable and discarded.
- Printed recordings offer a permanent record for later analysis.
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Description
This quiz explores Auditory Evoked Potentials (AEPs), the electrical signals produced by our auditory system in response to sound stimuli. Learn about their significance in assessing hearing integrity, their non-invasive measurement methods, and various classification approaches. Test your knowledge on the functioning and application of AEPs in auditory assessments.
