P17. Impaired auditory attention in adolescents with developmental dyslexia

Abstract

Theoretical background Developmental dyslexia (DD) refers to the pathological impairment in the acquisition of reading and/or writing skills that is not accounted for by biological age, intelligence or inadequate schooling (WHO, 2011). It is hypothesized that DD relies, at least in part, on the impaired ability to shift attention to relevant information (Hari and Renvall, 2001). On a neurophysiological level, attention is represented by alpha oscillations (about 8–12 Hz). In adults with DD, recent studies showed altered alpha oscillations during the processing of auditory and visual stimuli (Dhar et al., 2010) but also in resting state (Papagiannopoulou and Lagopoulos, 2016). However, until today, there is only sparse knowledge on auditory attention and the underlying neural mechanisms in adolescents with DD. Methods A sample of adolescents with diagnosed DD (Mean age: 14.29 years, SD: 1.46) and an age-matched control group (CG) participated in this study. In balanced order they performed two auditory spatial-cueing paradigms. In the exogenous paradigm, cue and target tones were presented monaurally at Stimulus onset Asynchrony (SOA) 100 ms and 250 ms. 50% of the trials consisted of valid cues. Catch trials (cue only) were intermittently presented. Participants had to respond as fast as possible whenever a target tone was presented. In the endogenous paradigm, cue and target tones were presented at SOAs between 1000 ms and 1500 ms. 80% of the trials consisted of valid cues. During both tasks EEG data was continuously recorded. Results While the CG showed an inhibition of return (IOR) i.e. reduced RT at invalid compared to valid cues with SOA 250 ms, no such effect was present in the DD sample. ERPs measured at the vertex electrode revealed prolonged peak latencies for target stimuli for both valid and invalid trials at SOA 250 ms in DD compared to CG. In the endogenous task, we found increased alpha desynchronization in the post-cue phase over left auditory cortex (AC) regions in DD compared to CG. Notably, this pattern was found irrespective of the site at which the cue was presented. Discussion The lack of an IOR in adolescents with DD demonstrates a decreased withdrawal of attention and suggests reduced orienting towards novel locations. Considering the endogenous task, our findings indicate a maladaptive inhibition of the left AC in DD that, in turn, might account for dysfunctional processing of incoming acoustic information. Our findings suggest altered auditory attention as potential basis for higher order language skills. Future studies investigating attention processes in pre-reading children will shed more light on whether attention is a cause of impaired language skills rather than the consequence of a maladaptive compensation over the course of reading/ writing acquisition.