Cortical Encoding of Pitch Contour Changes in Cochlear Implant Users: A Mismatch Negativity Study

Abstract

A better understanding of melodic pitch perception in cochlear implants (CIs) may guide signal processing and/or rehabilitation techniques to improve music perception and appreciation in CI patients. In this study, the mismatch negativity (MMN) in response to infrequent changes in 5-tone pitch contours was obtained in CI users and normal-hearing (NH) listeners. Melodic contour identification (MCI) was also measured. Results showed that MCI performance was poorer in CI than in NH subjects; the MMNs were missing in all CI subjects for the 1-semitone contours. The MMNs with the 5-semitone contours were observed in a smaller proportion of CI than NH subjects. Results suggest that encoding of pitch contour changes in CI users appears to be degraded, most likely due to the limited pitch cues provided by the CI and deafness-related compromise of brain substrates.

The MMN as a viable and objective marker of auditory development in CI users

“…Koelsch et al (2004) formed frontal, parietal, and left and right frontal ROI signals (frontal: Fz, F3, F4, FC3, and FC4; parietal: Pz, P3, P4, CP5 and CP6; frontal left: F3, F7, FC3, FT7; frontal right: F4, F8, FC4, FT8). Sandmann et al (2010) averaged (after ICA) the ERP signals from F1, Fz, F2, FC1, FCz and FC2 and Torppa et al (2014b) from the F3, Fz, F4, C3, Cz, and C4 electrodes (see also Zhang et al, 2013a). As Roman et al (2005a,b) state, these individual ROI waveforms may reveal the MMN more precisely.…”

“…A rather similar method for identifying individual MMN responses has been used by Zhang et al (2013a) who tested the melodic interval contour identification behaviorally and neurally using MMN responses. The 'standard' stimuli were the rising and falling contours with 1-or 5-semitone spacing.…”

“…Quite recently, Zhang et al (2013a) used the MMN to compare the ability of CI and NH adults to neurally and behaviorally detect the changes in melodic contours, presented with complex tones (f 0 and two harmonics). Several EEG oddball paradigms were presented to the participants, with the pitch interval between the tones in melodies being either one or five semitones.…”

“…Artefact-reduction with the ICA has been successfully used in several MMN studies on CI listeners (Sandmann et al, 2010;Zhang, 2011, Zhang et al, 2013aTimm et al, 2012, 2014, Torppa et al, 2012, 2014bPetersen et al, 2015;see Tables 1 and 2). Artefact reduction with the ICA can be very time-consuming.…”

Validation of the cochlear implant artifact correction tool for auditory electrophysiology

“…In theory, each component represents the activation of one independent contributing source to the averaged ERP, and thus artifactual components can be identified and linearly subtracted from the ICA matrix [8]. The majority of publications that have used the ICA approach relied on manual inspection to remove components representing CI artifact from EEG data [1,6,19,20]. This manual process is laborious, subjective, and requires expert knowledge.…”