Verbal working memory and inhibition-concentration in adults with cochlear implants.

OBJECTIVES

Neurocognitive functions contribute to speech recognition in postlingual adults with cochlear implants (CIs). In particular, better verbal working memory (WM) on modality-specific (auditory) WM tasks predicts better speech recognition. It remains unclear, however, whether this association can be attributed to basic underlying modality-general neurocognitive functions, or whether it is solely a result of the degraded nature of auditory signals delivered by the CI. Three hypotheses were tested: 1) Both modality-specific and modality-general tasks of verbal WM would predict scores of sentence recognition in speech-shaped noise; 2) Basic modality-general neurocognitive functions of controlled fluency and inhibition-concentration would predict both modality-specific and modality-general verbal WM; and 3) Scores on both tasks of verbal WM would mediate the effects of more basic neurocognitive functions on sentence recognition.

STUDY DESIGN

Cross-sectional study of 30 postlingual adults with CIs and thirty age-matched normal-hearing (NH) controls.

MATERIALS AND METHODS

Participants were tested for sentence recognition in speech-shaped noise, along with verbal WM using a modality-general task (Reading Span) and an auditory modality-specific task (Listening Span). Participants were also assessed for controlled fluency and inhibition-concentration abilities.

RESULTS

For CI users only, Listening Span scores predicted sentence recognition, and Listening Span scores mediated the effects of inhibition-concentration on speech recognition. Scores on Reading Span were not related to sentence recognition for either group.

CONCLUSION

Inhibition-concentration skills play an important role in CI users' sentence recognition skills, with effects mediated by modality-specific verbal WM. Further studies will examine inhibition-concentration and WM skills as novel targets for clinical intervention.

LEVEL OF EVIDENCE