Auditory gating in adults with dyslexia: An ERP account of diminished rapid neural adaptation.

OBJECTIVE

A recent functional magnetic resonance imaging (fMRI) study of adults with dyslexia showed a general deficit in suppressing responses to various types of repetitive stimuli. This diminished neural adaptation may interfere with implicit learning and forming stable word representations. With fMRI, spatial but not temporal characteristics of the adaptation response could be identified. We address this knowledge gap using event-related potentials.

METHODS

Fourteen adults with dyslexia and 14 controls participated in an auditory gating paradigm using tone pairs. Response amplitudes and latencies for N1 and P2 were measured. Participants also compared word pairs consisting of identical or subtly different words, a task requiring stable word representations.

RESULTS

Only the controls showed a robust gating effect in an attenuated N1 response to the second tone relative to the first. The dyslexia group was less accurate than the controls in detecting word differences. The N1 gating magnitude was associated with this detection accuracy.

CONCLUSIONS

Neural adaptation occurs by approximately 100 ms after stimulus presentation and is diminished in adults with dyslexia. This complements fMRI findings of relevant brain regions by implying a time window representing sensory and pre-attentive auditory processes.

SIGNIFICANCE

The association between gating magnitude and word discrimination contributes to a neurophysiological account of underspecified word representations.