title: Electrically evoked compound action potential artifact rejection by independent component analysis: technique validation.
abstract: The electrically-evoked compound action potential (ECAP) is the synchronous whole auditory nerve activity in response to an electrical stimulus, and can be recorded in situ on cochlear implant (CI) electrodes. A novel procedure (ECAP-ICA) to isolate the ECAP from the stimulation artifact, based on independent component analysis (ICA), is described here. ECAPs with artifact (raw-ECAPs) were sequentially recorded for the same stimulus on 9 different intracochlear recording electrodes. The raw-ECAPs were fed to ICA, which separated them into independent sources. Restricting the ICA projection to 4 independent components did not induce under-fitting and was found to explain most of the raw-data variance. The sources were identified and only the source corresponding to the neural response was retained for artifact-free ECAP reconstruction. The validity of the ECAP-ICA procedure was supported as follows: N1 and P1 peaks occurred at usual latencies; and ECAP-ICA and artifact amplitude-growth functions (AGFs) had different slopes. Concatenation of raw-ECAPs from multiple stimulus currents, including some below the ECAP-ICA threshold, improved the source separation process. The main advantage of ECAP-ICA is that use of maskers or alternating polarity stimulation are not needed.
authors: School of Psychological Sciences, Faculty of Medical and Human Sciences, The University of Manchester, Manchester M13 9PL, UK.
authors: Idrick
authors: I
authors: Akhoun
authors: Colette M
authors: CM
authors: McKay
authors: Wael
authors: W
authors: El-Deredy
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000368:Aged; D000669:Amplifiers, Electronic; D016477:Artifacts; D019929:Cochlear Implantation / Q000379:methods*; D003054:Cochlear Implants; D003056:Cochlear Nerve / Q000502:physiology; D004558:Electric Stimulation; D004566:Electrodes; D004867:Equipment Design; D005071:Evoked Potentials / Q000502:physiology*; D005072:Evoked Potentials, Auditory / Q000502:physiology; D006801:Humans; D008875:Middle Aged; D012815:Signal Processing, Computer-Assisted
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