general principles part 1 historical and classifications
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General Principles Part 1 Historical And ClassificationsTRANSCRIPT
Henry P. Trahan, Au.D.
AUD 744AUD 744Overview of Overview of
Auditory Evoked ResponsesAuditory Evoked ResponsesTransitional Audiology ProgramTransitional Audiology Program
AUD 616 AUD 616 Auditory Evoked ResponsesAuditory Evoked Responses
Residential Audiology ProgramResidential Audiology Program
Part 1 Part 1
Auditory Evoked Auditory Evoked ResponsesResponses
Historical OverviewHistorical Overview
And And
General PrinciplesGeneral Principles
1929 – Human EEG -- Berger 1930 – First paper on AEPs in general --
Weaver and Bray 1930 – Earliest of AEPs discovered
– Cochlear Microphonic – Weaver and Bray
1939 – First recorded alteration in EEG with auditory stim. in humans – P. Davis
1941 – CM recorded from round window in human through TM perforation – Pearlman and Case
Historical Time LineHistorical Time Line
Henry P. Trahan, Au.D.
1950 – Summating Potential in animal recorded – Davis
1958 – Description of average response computer (ARC) – Clark
1967 – AP with earlobe electrodes. ABR response first shown but
reported as ECochG – Sohmer and Feinmesser
1971 – AP recorded in human w/external ear canal electrode – Saloman & Elberling
Historical Time LineHistorical Time Line
Henry P. Trahan, Au.D.
1971 – ABR first described in animals - Jewett
1971 – ABR response first described in humans – Jewett, Romano, Williston
1974 – CM, SP, and AP record in human w/ ear canal electrode -- Coats
1974 – Relationship between ECochG abnormalities and Meniere’s disease – Eggermont
1974 – Description of ABR in infants & young children – Hecox and Galambos
Historical Time LineHistorical Time Line
Henry P. Trahan, Au.D.
Electrical potentials in the human nervous system can be recorded both in response to specific external stimuli (event-related potentials [ERP] ) and in an ongoing manner without the presence of external stimuli (non-evoked or non-event related).
Evoked Versus Evoked Versus
Non-EvokedNon-Evoked ResponsesResponses
Henry P. Trahan, Au.D.
Non-Event Related Event Related
EEG ECochG
ABR
Evoked Versus Evoked Versus Non-Evoked ResponsesNon-Evoked Responses
Henry P. Trahan, Au.D.
Auditory Evoked Responses (AERs) represent electrical responses of the Auditory nervous system to externally presented acoustic stimuli.
Henry P. Trahan, Au.D.
Auditory Evoked Auditory Evoked ResponsesResponses
1. AEPs can be classified according to whether their characteristics are determined by external or internal processes (exogenous vs. endogenous)
2. AEPs can be classified according to the time epoch following the stimulus in which they occur. (latency)
3. AEPs can be classified according to the relation of the recording electrodes to the actual generator sites. (Near Field vs. Far Field)
4. AEPs can be classified according to what structures in the auditory system generates them.
Henry P. Trahan, Au.D.
Classification of Auditory Evoked ResponsesClassification of Auditory Evoked Responses
Henry P. Trahan, Au.D.
Classification of Auditory Evoked ResponsesClassification of Auditory Evoked Responses
1. AEPs can be classified according to whether their characteristics are determined by external or internal processes.
Exogenous Endogenous
Jeffrey L. Alexander, Ph.D.
Classification of AEPsClassification of AEPs2. AEPs can be classified according
to the time epoch following the stimulus in which they occur.
– Very Early (0 – 1.5 msec) (First) (CM, SP, N1) (ECochG)
– Early (1.5 -12 msec) (Fast) Nerve and brainstem) (ABR)
– Middle (12 - 50 msec) (thalamus and aud. cortex) (MLR)
– Slow (50 – 300 msec) (1o and 2o areas of cortex) (ALR)
– P300 (300+ msec) (1o and association areas) (P300)
Jeffrey L. Alexander, Ph.D.
The Family of AEPsThe Family of AEPs
Jeffrey L. Alexander, Ph.D.
The Family of AEPsThe Family of AEPs
vertex positive
III
IIIIV V
VI
No
Po
Na
Pa
Nb
P1
N1
P2
N2
P300
Jeffrey L. Alexander, Ph.D.
Classification of AEPsClassification of AEPs
3. AEPs can be classified according to the relation of the recording electrodes to the actual generator sites.
– Far-Field Response (Electrodes some distance away)
– Near-Field Response (Electrodes in close proximity)
Jeffrey L. Alexander, Ph.D.
Clinically, AEPs are almost always recorded at far-field., with electrodes located outside of the skull (extracranially), usually at the scalp. Two exceptions are:
1. During intraoperative monitoring (when recording electrodes mat be placed directly on the VIIIth Nerve) and
2. During transtympanic membrane ECochG, (when a recording electrode may be placed on the promontory).
Jeffrey L. Alexander, Ph.D.
4. AEPs can be classified according to what structures in the auditory system generates them.
– Receptor Potentials (cochlear hair cells)
– Neurogenic Potentials (VIIIth N &/or brain stem)
Classification of AEPsClassification of AEPs