Mind over lungs: the impact of coping strategies on pulmonary rehabilitation outcomes.

As one of the most successful neural prostheses developed to date (), the cochlear implant (CI) has been used to restore hearing in both adult and pediatric patients for more than four decades. In current clinical practice, similar programming parameters are often applied to both adult and pediatric CI users, and manufacturers’ default settings are frequently used in both patient populations (). This practice implicitly assumes comparable neural encoding and processing of electrical stimulation across patient populations, as well as among CI users within each population. However, substantial differences between adult and pediatric CI populations in factors known to influence clinical outcomes call the validity of this assumption into question. In particular, the etiologies of hearing impairment differ markedly between these groups. For example, gap junction beta-2 (GJB2) mutations and congenital cytomegalovirus (CMV) infection are among the most common causes of hearing loss in children (e.g., (; ; ; ; ; )), whereas these etiologies are rarely observed in adult CI populations (; ). In contrast, presbycusis and noise exposure are prevalent causes of hearing loss in adult CI users but not in pediatric populations. In addition, inner ear malformations are present in approximately 20% of children with congenital sensorineural hearing loss (SNHL) (; ), yet such anatomical abnormalities are infrequently observed in adult CI users with bilateral SNHL (). Finally, adult CI users typically experience a substantially longer duration of deafness prior to implantation and are implanted at an older age compared with pediatric CI users. Collectively, these etiological, anatomical, and experiential differences are expected to influence the integrity and functional organization of the auditory pathway, thereby affecting the neural encoding and processing of electrical stimulation delivered by the CI. Indeed, substantial evidence demonstrates pronounced individual variability in neurophysiological responses to CI stimulation within both adult and pediatric populations (e.g., (; ; ; )). However, studies that directly compare neurophysiological responses to comparable electrical stimulation conditions following similar testing protocols between adult and pediatric CI users remain sparse (; ; ; ; ). As a result, whether electrical stimulation from a CI is encoded and processed in a similar manner across adult and pediatric patient populations remains poorly understood. To address this critical knowledge gap and advance the development of evidence-based clinical practices for determining optimal programming settings for individual CI users, we adopted a bottom-up approach to evaluate and compare cochlear nerve (CN) responsiveness to electrical stimulation in adult and pediatric CI users, using electrophysiological measures of the electrically evoked compound action potential (eCAP). The rationale for focusing on the CN is that it is the first auditory structure to encode electrical input delivered by the CI. As such, the fidelity with which the CN responds to and encodes electrical stimulation influences downstream neural processing and, ultimately, clinical outcomes. Consistent with this framework, converging evidence indicates that the health status of the CN — determined by both the number of activated CN fibers and the neural integrity of these activated fibers — is a critical determinant of speech perception performance in both adult and pediatric CI populations (; ; ; ; ). The present line of research in our laboratory comprises multiple projects that assess and compare eCAPs evoked by single pulses and by trains of electrical pulses in postlingually deafened adult and pediatric CI users. It was motivated by the lack of objective physiological data characterizing potential differences in neural responsiveness across commonly encountered CI user populations. By comparing neural responsiveness between pediatric and adult CI users, this line of research aimed to provide an initial framework for understanding how these measures may vary across clinically relevant groups and to inform future work toward more individualized approaches to CI fitting and evaluation. The present study reports results for two eCAP metrics that assess CN health status. Additional findings will be reported in companion publications within this series. The first eCAP metric included in this study is the phase locking value (PLV), which serves as an index of neural synchrony in the CN (). The second eCAP metric is the effect of increasing the interphase gap (IPG) of biphasic pulses on the eCAP (i.e., the IPG effect), which primarily reflects the number of CN fibers activated by electrical stimulation (He et al., 2026). These two metrics were selected because their underlying biological bases are critically relevant to CI clinical outcomes, as detailed below.