22359
Testing Auditory Brainstem Responses in Low-Functioning Children with ASD
The neurological underpinnings of ASD language have long been sought, both to shed light on possible causes of the complex and multi-faceted behavioral presentation, and to identify targets for intervention. The purpose of our overall project is to explore whether abnormalities in language development can be attributed to breakdowns at an early stage of auditory processing, namely the auditory brainstem. Recent research with individuals with ASD has converged on the finding that abnormal neural conduction time, as revealed by prolonged latencies of auditory brainstem response (ABR), is a hallmark of the ASD central auditory system (Rosenhall et al., 2003; Roth et al., 2012; Russo et al., 2009). Most studies have involved high-functioning children tested in a lab setting; however, data collection from a wider range of children and in a home setting is desirable.
Objectives:
The purpose of the current study was to validate our ABR data collection protocol with low-functioning children tested at home.
Methods:
Two boys, aged 6 and 15 years, were tested. At their most recent assessment, their DAS NVIQs were 69 and 45 respectively, with TACL-Q standardized language scores of 57 and 61, respectively, and ADOS scores of 26 and 13, respectively. ABRs were recorded from scalp electrodes in response to a click stimulus (31.1/sec, 2000 trials) and a 40 millisecond “da” stimulus (10.9/sec, 6000 trials) presented at 80 dB SPL to the right ear. Wave V, the most robust peak within the ABR, serves as the primary dependent measure of sound encoding in this study.
Results:
Both boys were able to tolerate the electrode application and sound stimulation. Moreover, both provided useable ABR data, with minimal movement artifacts. In Figure 1, our pilot data is compared to the speech-evoked ABR waveforms of the TD and (high functioning) ASD groups from Russo et al., 2009. In our data, Wave V is clearly delineated; the latency and amplitude variability is also consistent with the ASD sample from Russo et al. (plotted as grey lines).
Conclusions:
Our procedures for collecting ABR data at home from two low-functioning boys with ASD proved successful, yielding waveforms that resembled those collected in lab settings, and demonstrating feasibility of collecting reliable ABR’s in this setting and with this type of child. In the next 6 months we will collect ABR data from at least 8 more children with ASD, including both high- and low-functioning children, and assess the relationships between their ABRs and language abilities.