Peripheral neural status and auditory temporal resolution in cochlear implant users

Auditory temporal resolution is important for understanding speech with a cochlear implant (CI). The aim of this study was to determine the relative contributions of peripheral neural synchrony and peripheral neural survival to perceptual temporal resolution in CI users. To date, study participants included 8 post-lingually deafened adult CI users. All participants used Cochlear™ Nucleus® devices in their test ears. For each implanted ear tested in each participant, auditory temporal resolution, neural synchrony, and neural survival were evaluated at multiple electrode locations along the array. Auditory temporal resolution was estimated using single-channel, psychophysical gap detection thresholds (GDTs), peripheral neural synchrony was estimated using the phase-locking value (PLV), and peripheral neural survival was estimated using the sensitivity of the electrically-evoked compound action potential to changes in interphase gap (i.e., IPG effect). After adjusting for multiple comparisons, our preliminary results indicated that GDT was significantly correlated with the PLV but not with the IPG effect. The PLV and the IPG effect were not significantly correlated. These preliminary results suggested that the degree of peripheral neural synchrony appeared to play a more important role in determining auditory temporal resolution than peripheral neural survival. [Work supported by NIH: 1R01 DC016038, 1R01 DC017846, R21 DC019458]