A neural oscillations perspective on phonological development and phonological processing in developmental dyslexia

Abstract

Children's ability to reflect upon and manipulate the sounds in words (“phonological awareness”) develops as part of natural language acquisition, supports reading acquisition, and develops further as reading and spelling are learned. Children with developmental dyslexia typically have impairments in phonological awareness. Many developmental factors contribute to individual differences in phonological development. One important source of individual differences may be the child's sensory/neural processing of the speech signal from an amplitude modulation (~energy or intensity variation) perspective, which may affect the quality of the sensory/neural representations (“phonological representations”) that support phonological awareness. During speech encoding, brain electrical rhythms (oscillations, rhythmic variations in neural excitability) recalibrate their temporal activity to be in time with rhythmic energy variations in the speech signal. The accuracy of this neural alignment or “entrainment” process is related to speech intelligibility. Recent neural studies demonstrate atypical oscillatory function at slower rates in children with developmental dyslexia. Potential relations with the development of phonological awareness by children with dyslexia are discussed.

Processing of Rhythm in Speech and Music in Adult Dyslexia

“…Since rhythmic grouping preferences are asymmetrical between the perceived acoustic cues, these biases cannot simply be accounted for by a tracking of acoustic cues to prominence in the signal. Importantly, asymmetries in rhythmic grouping are mirrored in the rhythm structures in language and music where final prominence is usually marked by a long syllable or note, and initial prominence by a loud syllable or beat, which supports the assumption of the ITL as universal [19]. More recent research, however, indicates that rhythmic grouping preferences are subject to individual variation and depend to some degree on aspects such as individuals' language background [38,[47][48][49][50] and their musical abilities [51,52].…”

“…Goswami [5,19] has proposed that a fundamental deficit in the processing of rhythmic information is associated with dyslexia. This account focuses on the periodic modulations of amplitude (amplitude envelope) that are crucial to establish speech rhythm with amplitude peaks being aligned with the strong (stressed) syllables of a speech sequence and Goswami assumes that the processing of this amplitude envelope is impeded in dyslexia.…”

Advances in the Neurocognition of Music and Language

“…In a similar vein, rhythmic-prosodic sensitivity has been proposed as fundamental stepping stone into literacy [27][28][29] as well as implicit driver for skilled reading [30]. Breen et al [11] and Fotidzis et al [8] present converging EEG evidence for implicit rhythmic processing in silent reading of words in literate adults and children.…”

“…Current neurophysiological models assume that speech and music processing as well as the catalytic role of rhythm in language development are based on the synchronization of internal neuronal oscillations with temporally regular stimuli [27,[31][32][33]. The review article by Myers et al [15] summarizes the current state of knowledge about neuronal entrainment to the speech envelope reflecting quasi-regular amplitude fluctuations over time.…”

“…This raises the questions of how much training is required and which aspects the training should include to translate to behavior, both inside and outside the laboratory setting. Clearly, the identification of optimal interventions is a joint mission for future research that goes hand in hand with the development of solid conceptual [ 41 , 42 ] and neurophysiological frameworks [ 27 ] to identify the key variables underlying the amelioration of speech and language processing through rhythm and music [ 43 , 44 , 45 , 46 ].…”