Auditory Evoked Potentials as a Window into Word Learning in Dyslexia: Mismatch Negativity, Response Time and Accuracy, and Associated Language Deficits

Objective: Previous studies have observed that adults with dyslexia display a reduced N1 gating when exposed to repetitive stimuli. Robust gating is associated with the ability to recognize familiar stimuli and identify the stimuli that will need novel memory representations formed. This study investigates if the mismatch negativity component in electroencephalographic-produced Event-Related Potentials (ERPs) is affected as well by diminished memory forming in adults with dyslexia. Additionally, signal/ noise processing for auditory-based memory recollection and thus word learning is explored. Methods: Nineteen adults with dyslexia and 18 adult controls participated in a classic auditory oddball electroencephalographic experiment here referred to as DIFF, to indicate that the tones differed in frequency, while incorporating a decision-making task that signified participant tonal discrimination. Mismatch Negativity (MMN) amplitudes (AMPs) and latencies were collected from ERPs. Behavioral data consisting of reaction time (RT) and accuracy (ACC) of tone choice were documented. Results: Group differences for accuracy and reaction time in the DIFF task were highly significant. The dyslexic group produced longer reaction times and with less accuracy than the control group. The Mismatch Negativity amplitude and latency collected did not differ significantly between groups, however, correlations to other variables obtained from similar studies consisting of the same participant group were observed. Linear regression models indicated predictions for accuracy and reaction time results based upon WID scores (Word Identification Test) and SWE scores (Sight Word Efficiency) respectfully. Conclusions: Neural processing speed and the ability to form permanent memory representations of auditory sound bites for retrieval is dampened in dyslexic populations. Significance: To better illuminate and understand the neural mechanisms of dyslexia, specifically auditory processing, with the goal of improving outcomes in individuals with dyslexia through more efficient therapy treatment options.