Three studies were conducted to address gaps in knowledge pertaining to the use of auditory evoked electrophysiological measures as potential biomarkers for neurodevelopmental communication dis-orders. Some subjects with these disorders demonstrate auditory tem-poral processing deficits, which may have a basis in impaired myelin within the auditory brainstem. Given their sensitivity to such deficits and their feasibility for use with very young infants, electrophysiolog-ical measures make feasible candidates as biomarkers for these disor-ders. In particular, a subset of neonatal Intensive Care Unit graduates show a transient failure of the auditory brainstem response (ABR) at newborn hearing screening that may indicate an onset of impaired myelin. The study in Chapter Three was conducted to investigate the hypothesis that this transient failure may be associated with communi-cation difficulties in later childhood. No association was found be-tween this transient failure and communication ability. However, pa-rental concern over general development of a child was found to be a potentially useful marker for children who demonstrated communica-tion difficulties. Some subjects with neurodevelopmental communica-tion disorders also show atypical frequency following responses (FFRs). The FFR is not currently used in a clinical setting, despite evidence that it may be more sensitive to auditory temporal processing deficits than the ABR. The results of the study in Chapter Four showed that group delay latency of the FFR, which represents where in the auditory brainstem the response is likely to be generated, occurs significantly later than latency of the click-evoked ABR wave V, which signals the offset of this response. These results indicate that the FFR may reflect auditory processing efficiency in separate struc-tures of the auditory brainstem and therefore, provide more insight into temporal synchronicity than the ABR alone. However, the study in Chapter Five found that the FFR could not distinguish adults with a neurodevelopmental communication disorder from a control group. In contrast, adults with Autism Spectrum Disorder (ASD) could be distinguished from a control group by the wave III-V inter-peak latency of the click-evoked ABR. Prolongation of this inter-peak latency was also found in adults with a demyelinating disorder. These results suggest that the auditory temporal processing deficits in ASD may have a basis in impaired myelination that can be measured by inter-peak interval latency of the click-evoked ABR. However, a behavioural measure of speech-in-noise ability was found to be a more important predictor of the presence of a communication disorder than the wave III-V inter-peak latency. Overall, the findings of the studies in this thesis shed new light on the potential usefulness of auditory evoked electrophysiological measures as potential biomarkers for neurodevelopmental communication disorders.
|Date of Award
|1 Aug 2016
- The University of Manchester
|Kai Uus (Supervisor) & Chris Plack (Supervisor)