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Active and passive processing of novel acoustic stimuli in cochlear-implant patients: An EEG studyDFG Exzellenzcluster EXC 1077/1 "Hearing4all"
18 April 2018 (online)
To adequately process novel acoustic stimuli in the environment, a good balance between bottom-up and top-down processes is needed. Only in this way one can appropriately react to these stimuli and possible threats can be detected in time. The interaction between bottom-up and top-down processes in cochlear-implant (CI) patients, and its influence on CI performance are not well understood yet.
In the study, 20 CI patients and 20 normal-hearing (NH) controls performed a three-stimulus oddball paradigm, including standard (70%), target/deviant (15%), and unique environmental sounds (15%). The task was carried out once actively and once passively. During the task, electroencephalography (EEG) and behavioral data were recorded, which were compared between groups and conditions.
Initial data point to an attenuated sensory processing in CI patients, whereby the cognitive processing seems comparable to the NH. Both, CI patients and NH show a bottom-up-related early and a top-down-related late Novelty-P3, with the late Novelty-P3 being reduced in the passive condition for both groups. Group differences show up for the amplitudes of the early, but not the late Novelty P3.
The current study enables the objective comparison of the active and passive processing of novel acoustic stimuli in CI patients. The observed impairment in bottom-up processes for CI-degraded listening, and the simultaneous preserved top-down processing suggest a shift of the balance in CI patients in contrast to NH.