Delta EEG activity as a marker of dysfunctional linguistic processing in developmental dyslexia

Abstract

The present study used delta EEG band to test the hypothesis of a cerebral maturational delay and a functional altered cerebral asymmetry for phonological processing in dyslexic children. A group of 14 children with dyslexia and 28 matched controls participated in a linguistic paradigm in which the same words were processed in three tasks: phonological, semantic, and orthographic. Delta amplitude was computed as an index of cortical inhibition in four different phases of word processing. In anterior sites, controls showed left activation (reduced delta) during the phonological task and bilateral activation in the other two tasks. Conversely, children with dyslexia showed greater overall delta amplitude, indexing a cerebral maturation delay and an altered language laterality pattern. In the phonological task they had larger left anterior delta (inhibition of left frontal linguistic locations) and smaller left posterior delta amplitude (activation of left posterior sites silent in controls). Results support the phonological deficit hypothesis of developmental dyslexia and the validity of EEG delta band as functional and clinical measure of language laterality.

Preliteracy signatures of poor-reading abilities in resting-state EEG

“…If slow-wave delta activity is indeed a necessary mechanism for pruning and cortical development to take place, our finding of reduced delta-1 activity seem to be in agreement with the hypothesis of a cerebral maturation delay in 3-year old children that later on become poor readers. Later in life, delta waves remain dominant during slow-wave sleep; however, a relatively high delta activity in a wakeful state has been associated with pathological neuronal conditions (Spironelli and Angrilli, 2009; Babiloni et al, 2012) such as in adults with ADHD and dyslexia (Chabot et al, 2001; Penolazzi et al, 2008). Higher delta activity has also been observed in dyslexic school-age children (Spironelli et al, 2006; Penolazzi et al, 2008; Spironelli and Angrilli, 2010) and dyslexic young adults (Rippon, 2000), although these data were recorded during reading tasks.…”

“…Later in life, delta waves remain dominant during slow-wave sleep; however, a relatively high delta activity in a wakeful state has been associated with pathological neuronal conditions (Spironelli and Angrilli, 2009; Babiloni et al, 2012) such as in adults with ADHD and dyslexia (Chabot et al, 2001; Penolazzi et al, 2008). Higher delta activity has also been observed in dyslexic school-age children (Spironelli et al, 2006; Penolazzi et al, 2008; Spironelli and Angrilli, 2010) and dyslexic young adults (Rippon, 2000), although these data were recorded during reading tasks. However, increased delta and theta activity in dyslexics or children with reading and writing disabilities have also been reported in resting-state EEG at the age of 9–18 years (Sklar et al, 1972; Colon et al, 1979; Pinkerton et al, 1989; Harmony et al, 1995).…”

“…Comparing these two groups has pointed to higher delta and theta activity during phonological task (Rippon, 2000; Klimesch et al, 2001a; Spironelli et al, 2006; Penolazzi et al, 2008) and lower alpha and beta activity (Rumsey et al, 1989; Rippon, 2000; Klimesch et al, 2001b) during reading tasks in dyslexics. Several studies (Sklar et al, 1972; Colon et al, 1979; Ahn et al, 1980; Duffy et al, 1980; Pinkerton et al, 1989; Rumsey et al, 1989; Harmony et al, 1995; Clarke et al, 2002; Benasich et al, 2008; Gou et al, 2011; Babiloni et al, 2012) have also investigated EEG from the resting-state.…”

Differential effects of aging on EEG after baclofen administration

“…For example, when the delta rhythm appears in wakefulness, it can be considered as a marker of brain damage or pathological conditions resulting from neurological damage or psychiatric disease [28][29][30]. Based on these data, we hypothesize that the age-related EEG changes in the delta band induced by baclofen may indicate that some pathological changes occurred during aging.…”

Educational neuroscience: Developmental mechanisms: Towards a conceptual framework

“…For example, if low frequency phase locking in auditory cortex is inefficient (for example, in developmental dyslexia, where Theta and Delta phase locking appears impaired, see Penolazzi et al, 2008;Soltesz et al, 2010), this would affect both the sensory representation of speech and potentially have knock-on effects for multisensory integration in STS (and for multisensory attention). Similarly, if a mechanism such as cross-frequency phase synchronisation between Theta and Gamma oscillations at posterior parietal recording sites determines the capacity of visual working memory (Sauseng et al, 2009), then impaired phase synchronisation at these sites would seem likely to impair working memory capacity and have consequent effects on cognitive control.…”