Audio-Tactile Integration in Congenitally and Late Deaf Cochlear Implant Users

Abstract

Several studies conducted in mammals and humans have shown that multisensory processing may be impaired following congenital sensory loss and in particular if no experience is achieved within specific early developmental time windows known as sensitive periods. In this study we investigated whether basic multisensory abilities are impaired in hearing-restored individuals with deafness acquired at different stages of development. To this aim, we tested congenitally and late deaf cochlear implant (CI) recipients, age-matched with two groups of hearing controls, on an audio-tactile redundancy paradigm, in which reaction times to unimodal and crossmodal redundant signals were measured. Our results showed that both congenitally and late deaf CI recipients were able to integrate audio-tactile stimuli, suggesting that congenital and acquired deafness does not prevent the development and recovery of basic multisensory processing. However, we found that congenitally deaf CI recipients had a lower multisensory gain compared to their matched controls, which may be explained by their faster responses to tactile stimuli. We discuss this finding in the context of reorganisation of the sensory systems following sensory loss and the possibility that these changes cannot be “rewired” through auditory reafferentation.

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

“…The redundant signals effect (i.e., significantly faster RTs to the audio–visual compared with the fastest modality‐specific condition) was recognized in each group. This effect has been previously reported in NH listeners [e.g., Girard et al, ; Mahoney et al, ] and in CI patients [e.g., Nava et al, ; Schierholz et al, ]. Hence, our results extend previous findings by showing that a redundant signals effect also exists in patients with central auditory prostheses.…”

“…Regarding CI patients, the Gain RT was not as strong. This is in line with findings of earlier studies, reporting no difference in multisensory Gain RT between post-lingually deafened CI patients and NH listeners [Nava et al, 2014;Schierholz et al, 2015]. The discrepancy between the groups of patients might be caused by the differential use of compensation strategies.…”

Enhanced audio–visual interactions in the auditory cortex of elderly cochlear-implant users

“…All four groups showed a remarkable audioevisual gain, which was comparable between the two hearing groups (NH, CI) and the two age groups (young, elderly). This replicates the finding from a previous study which reported comparable multisensory gain for audio-tactile processing in late-deafened CI users and NH listeners (Nava et al, 2014). Interestingly, the same study observed a lower multisensory gain specifically in early deafened CI users (Nava et al, 2014).…”

“…This replicates the finding from a previous study which reported comparable multisensory gain for audio-tactile processing in late-deafened CI users and NH listeners (Nava et al, 2014). Interestingly, the same study observed a lower multisensory gain specifically in early deafened CI users (Nava et al, 2014). Together with the results of early deafened CI children, the findings of early deafened (late implanted) adult CI users suggest that hearing loss at young age can lead to decreased multisensory interactions and stronger dominance of vision (Gilley et al, 2010;Schorr et al, 2005).…”

Listening to another sense: somatosensory integration in the auditory system

“…Investigations aimed to understand whether this plasticity is dependent on the extent of hearing loss revealed that while the auditory association areas are activated in subjects with total or partial hearing loss, AI was activated only in the subjects with total hearing loss (Lambertz, et al, 2005). Interestingly, studies in subjects with temporary auditory deprivation that was restored by cochlear implants showed that temporary deafness can impair multisensory (audio-tactile) integration (Landry, et al, 2013, Nava, et al, 2014). More specifically, the subjects were tested using the audiotactile illusory-flash effect (Hotting and Roder, 2004) in which simultaneous presentation of a somatosensory stimulus with a large number of successive non-speech sounds can lead to as many tactile as auditory perceptions in normal hearing individuals.…”