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Αλέξανδρος Γ. Σφακιανάκης

Friday, May 21, 2021

Spectral features of cortical auditory evoked potentials inform hearing threshold and intensity percepts in acoustic and electric hearing

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J Neural Eng. 2021 May 19. doi: 10.1088/1741-2552/ac02db. Online ahead of print.

ABSTRACT

Stimulus-elicited changes in electroencephalography (EEG) recordings can be represented using Fourier magnitude and phase features (Makeig et al., 2004). The present study aimed to quantify how much information about hearing responses are contained in the magnitude, quantified by event-related spectral perturbations (ERSP); and the phase, quantified by inter-trial coherence (ITC). By testing if one feature contained more information and whether this information was mutually exclusive to the features, we aimed to relate specific EEG magnitude and phase features to hearing perception. Relating hearing perception to a measure such as EEG which does not require behavioral feedback from the listener is important in both neuroscience research and clinical audiology. EEG responses were recorded from twenty adults who were presented with acoustic stimuli, and tw enty adult cochlear implant users with electrical stimuli. Both groups were presented with short, 50 ms stimuli at varying intensity levels relative to their hearing thresholds. Extracted ERSP and ITC features were inputs for a linear discriminant analysis classifier (Wong et al., 2016). The classifier then predicted whether the EEG signal contained information about the sound stimuli based on the input features. Classifier decoding accuracy was quantified with the mutual information (MI) measure (Cottaris et al., 2009; Hawellek et al., 2016), and compared across the two feature sets, and to when both feature sets were combined. We found that classifiers using either ITC or ERSP feature sets were both able to decode hearing perception, but ITC-feature classifiers were able to decode responses to a lower but still audible stimulation intensity, making ITC more useful than ERSP for hearing threshold estimation. We also found that combining the information from both feature sets did no t improve decoding significantly, implying that ERSP brain dynamics has a limited contribution to the EEG response, possibly due to the stimuli used in this study.

PMID:34010826 | DOI:10.1088/1741-2552/ac02db

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