Auditory and audio–visual processing in patients with cochlear, auditory brainstem, and auditory midbrain implants: An EEG study

Abstract

There is substantial variability in speech recognition ability across patients with cochlear implants (CIs), auditory brainstem implants (ABIs), and auditory midbrain implants (AMIs). To better understand how this variability is related to central processing differences, the current electroencephalography (EEG) study compared hearing abilities and auditory-cortex activation in patients with electrical stimulation at different sites of the auditory pathway. Three different groups of patients with auditory implants (Hannover Medical School; ABI: n = 6, CI: n = 6; AMI: n = 2) performed a speeded response task and a speech recognition test with auditory, visual, and audio-visual stimuli. Behavioral performance and cortical processing of auditory and audio-visual stimuli were compared between groups. ABI and AMI patients showed prolonged response times on auditory and audio-visual stimuli compared with NH listeners and CI patients. This was confirmed by prolonged N1 latencies and reduced N1 amplitudes in ABI and AMI patients. However, patients with central auditory implants showed a remarkable gain in performance when visual and auditory input was combined, in both speech and non-speech conditions, which was reflected by a strong visual modulation of auditory-cortex activation in these individuals. In sum, the results suggest that the behavioral improvement for audio-visual conditions in central auditory implant patients is based on enhanced audio-visual interactions in the auditory cortex. Their findings may provide important implications for the optimization of electrical stimulation and rehabilitation strategies in patients with central auditory prostheses. Hum Brain Mapp 38:2206-2225, 2017. © 2017 Wiley Periodicals, Inc.

Combined Brain-Perfusion SPECT and EEG Measurements Suggest Distinct Strategies for Speech Comprehension in CI Users With Higher and Lower Performance

“…In total, 10 CI users were stimulated on the left and 11 on the right side. Similar to previous studies (e.g., Sandmann et al, 2015 ; Schierholz et al, 2017 ), the participants used a 7-point loudness-rating scale, which allowed adjusting the perceived loudness of the sentences to a comfortable level, equivalent to 60–70 dB ( Allen et al, 1990 ; Zeng, 1994 ).…”

“…The engagement of occipital areas might be related to the fact that although sentences are presented purely auditorily, they might be internally visualized. Furthermore, it has been previously reported that CI users show an enhanced audiovisual coupling (Schierholz et al, 2015(Schierholz et al, , 2017Strelnikov et al, 2015b) and that activation of the visual cortex by auditory stimulation is positively related to the CI performance (Giraud et al, 2001b,c;Strelnikov et al, 2013;Chen et al, 2016), indicating that cross-modal reorganization in the visual cortex and enhanced audiovisual coupling support speech processing in CI users.…”

AVATAR Assesses Speech Understanding and Multitask Costs in Ecologically Relevant Listening Situations

“…First, with regard to visual speech cues, more and more auditory-visual speech tests have been developed that include virtual talking heads or video recordings of real humans (e.g. Schierholz et al 2017;Schreitmüller et al 2018). Also, both virtual and real visual cues have successfully been included in dual-task studies investigating effortful listening (Fraser 2010, Gosselin & Gagné 2011, Stevens et al 2013Desjardins 2016).…”

Distinct multisensory perceptual processes guide enhanced auditory recognition memory in older cochlear implant users

“…Previous studies using unisensory auditory stimuli have reported that N1, N2 and P3a/P3b ERPs of CI users are reduced in amplitude and/or prolonged in latency when compared to NH listeners, suggesting difficulties in the sensory (N1) and the higher-level cognitive processing (N2 and P3a/P3b) of the limited CI input ( Finke et al, 2016 , Finke et al, 2015 , Henkin et al, 2014 , Henkin et al, 2009 , Sandmann et al, 2009 ). ERP differences between CI users and NH listeners have also been reported in studies using basic audio-visual stimuli , pointing to an enhanced visual modulation of auditory ERPs in elderly CI users when compared to NH listeners ( Schierholz et al, 2017 , Stropahl et al, 2015 ). Based on these ERP results and on the observation of a multisensory facilitation effect in NH listeners, we predicted that implanted individuals show a significant audio-visual facilitation for auditory object recognition as well.…”

“…These adaptations may also affect interactions between the different sensory modalities ( Lomber et al, 2010 , Rouger et al, 2007 , Schierholz et al, 2015 , Schorr et al, 2005 , Strelnikov et al, 2015 ). In particular, post-lingually deaf CI users show cross-modal reorganization in the auditory cortex ( Rouger et al, 2012 , Sandmann et al, 2012 ) and reveal stronger audio-visual interactions in the auditory cortex when compared with normal-hearing listeners ( Schierholz et al, 2017 ). These cortical alterations in CI users may allow better lip-reading abilities and enhanced audio-visual integration skills ( Stropahl et al, 2017 , Stropahl et al, 2015 ), fostering speech-comprehension recovery after cochlear implantation ( Strelnikov et al, 2013 ).…”