A stimulus-brain coupling analysis of regular and irregular rhythms in adults with dyslexia and controls

Abstract

When listening to temporally regular rhythms, most people are able to extract the beat. Evidence suggests that the neural mechanism underlying this ability is the phase alignment of endogenous oscillations to the external stimulus, allowing for the prediction of upcoming events (i.e., dynamic attending). Relatedly, individuals with dyslexia may have deficits in the entrainment of neural oscillations to external stimuli, especially at low frequencies. The current experiment investigated rhythmic processing in adults with dyslexia and matched controls. Regular and irregular rhythms were presented to participants while electroencephalography was recorded. Regular rhythms contained the beat at 2 Hz; while acoustic energy was maximal at 4 Hz and 8 Hz. These stimuli allowed us to investigate whether the brain responds non-linearly to the beat-level of a rhythmic stimulus, and whether beat-based processing differs between dyslexic and control participants. Both groups showed enhanced stimulus-brain coherence for regular compared to irregular rhythms at the frequencies of interest, with an overrepresentation of the beat-level in the brain compared to the acoustic signal. In addition, we found evidence that controls extracted subtle temporal regularities from irregular stimuli, whereas dyslexics did not. Findings are discussed in relation to dynamic attending theory and rhythmic processing deficits in dyslexia.

Is atypical rhythm a risk factor for developmental speech and language disorders?

“…It is possible that the same process might extend to language and allow for higher-level structure learning and processing. This hypothesis is supported by studies showing that neural oscillations entrain not only to physically marked beats and stressed syllables, but also to higher-level structures both in music (e.g., the metrical structure; Nozaradan, Peretz, Missal, & Mouraux, 2011 ) and language (e.g., syntactic structure; Ding, Melloni, Zhang, Tian, & Poeppel, 2015 ), which are not necessarily physically present in the signal ( Fiveash et al, 2020 ; Tal et al, 2017 ). Efficient entrainment, defined here as the precise phase-locking of neural oscillations at the appropriate frequency, to higher-level structures in musical rhythm and language may also lead to improved prediction skills, possibly through attention allocation (e.g., Large & Jones, 1999 ; Schmidt-Kassow & Kotz, 2009 ).…”

Linguistic syncopation: Meter-syntax alignment affects sentence comprehension and sensorimotor synchronization

“…This has implications for a number of theoretical and applied areas. Children with developmental language disorders (such as dyslexia) are thought to have impaired metrical entrainment and sensorimotor synchronization abilities, in both linguistic and musical contexts (Colling et al, 2017;Cumming et al, 2015;Fiveash, Schön, et al, 2020;Huss et al, 2011). They are also less sensitive to the alignment between meter and syntax (Richards & Goswami, 2019).…”

Rapid Assessment of Non-Verbal Auditory Perception in Normal-Hearing Participants and Cochlear Implant Users

“…Indeed, these visual cues did not provide the correct answer to perform the task, but rather gave information about the onset of the sounds. As the visual cues were not informative regarding the pitch of the tones, the visual information with its adequate timing might boost participants’ dynamic attendance to the onsets of the tones, as the tones were presented in a regular, isochronous sequence in the PCD task [ 116 , 117 , 118 ]. We found only weak evidence, if any, for an improvement of performance in audio-visual trials compared to audio-only trials in CI users.…”