Case Report: Neural correlates of orthographic congruency effects in auditory rhyme judgment in two stroke survivors

Background Auditory rhyme judgment has been widely used as an index of phonological processing in people with aphasia (PWA). However, healthy, literate adults experience orthographic interference during phonological tasks such as auditory rhyme judgment, a byproduct of skilled reading and crossmodal connections forged during reading acquisition. This orthographic interference is an indicator that orthographic representations are active during phonological processing. Therefore, the potential for orthographic interference in auditory rhyme judgments in PWA may indicate that performance on such tasks is supported by stored graphophonemic representations, rather than specifically indexing phonological processing. Method Using event related potentials (ERPs), we examined orthographic congruency effects in auditory rhyme judgment in two stroke survivors, one with moderate nonfluent aphasia and apraxia of speech, and one with mild nonfluent aphasia and apraxia of speech. The two stroke survivors and nine healthy comparison participants completed an auditory rhyme judgment task in four conditions (rhyming and non-rhyming, with congruent and incongruent orthography). Results ERP results showed the N400 rhyming and orthographic congruency effects for both stroke survivors and the comparison group even though words were not presented visually. Conclusion The results of this case report indicate that orthographic representations are active during auditory rhyme judgment in the two stroke survivors, similar to comparison participants. Thus, auditory rhyme judgment tasks may be supported by orthographic representations and therefore may not index solely phonological processing, but rather crossmodal graphophonemic representations.