Changed functional connectivity at rest in functional illiterates after extensive literacy training

Abstract

Background About 6.2 million adults in Germany cannot read and write properly despite attending school for several years. They are considered to be functional illiterates (FI). Since the ability to read and write is crucial for being employed and socially accepted, we developed a special literacy training to overcome these deficits. Methods In this study, we investigate training-related changes in intrinsic functional connectivity (iFC) at rest in a group of 20 FI and 20 adult normal readers using resting state functional magnetic resonance imaging (rsfMRI). We used independent component analysis (ICA) to define different networks. Results Before training, the between group analysis showed increased iFC in FI in a left-fronto-parietal network (LFPN; anterior insula, medial frontal cortex, lateral and frontal parietal regions) and in the Basal Ganglia network (BGN: thalamus, caudate, putamen, pallidum, amygdala, supplementary motor cortex and cingulate gyrus). Furthermore, the Visual Network-1 (VN1; temporal occipital fusiform gyrus, lateral occipital cortex, occipital pole, lingual gyrus, thalamus) showed decreased iFC in FI. After training the FI group showed reversal of the “hyperconnectivity” in middle frontal gyrus and in the frontal orbital cortex and between supramarginal gyrus and the BGN. Furthermore, functional connectivity increased in FI VN1 (lateral occipital cortex, insular cortex). These changes in connectivity correlated with gains in reading speed and spelling accuracy. Conclusions These findings show that poor reading and writing abilities are associated with abnormalities in iFC in several brain areas subserving cognitive processes important for reading. Intensive literacy training induces changes in the functional connectivity between and within neural networks important for literacy skills.

Learning to read Chinese promotes two cortico-subcortical pathways: The development of thalamo-occipital and fronto-striatal circuits

“…In fact, the answer is no. Several studies based on alphabetic language reading have found that this pathway plays an important role ( Alcauter et al, 2017 ; Hancock et al, 2017 ; Mohammadi et al, 2020 ). Third, is fronto-striatal connectivity stronger in Chinese reading than in alphabetic language reading?…”

“…The study of illiteracy training belongs to the early stage of reading development, so the thalamus is the most prominent and easy to discover. For example, another study of training based on functional illiteracy found that although the connectivity strength of the fronto-striatal and thalamo-visual pathways was significantly lower in the illiterate group than in the control group, only the thalamic network, not the striatum network, was enhanced after a short training session ( Mohammadi et al, 2020 ). This finding suggests that the thalamic network is more likely to be increased early in training, while the striatum network requires more training time to become more involved in reading ability.…”

“…In one resting-state functional magnetic resonance imaging (fMRI) study of illiterate adults, Skeide et al (2017) observed that a 6-month literacy intervention altered the cortico-subcortical crosstalk in the visual system of illiterate individuals. Some studies, including studies based on comparisons between children and adults ( Koyama et al, 2020 ), literacy training studies ( Alcauter et al, 2017 ; Hancock et al, 2017 ; Koyama et al, 2020 ; Mohammadi et al, 2020 ), and child development studies, ( Alcauter et al, 2017 ) also found that cortico-subcortical alterations play an important role at the early stage of learning to read. Among these alterations, the most frequently affected subcortical structures were the striatum and thalamus.…”

“…The dysfunction of fronto-striatal circuits was confirmed by a meta-analysis to cause fundamental impairments in reading-related processing ( Hancock et al, 2017 ). Fronto-striatal functional connectivity was significantly weaker in illiterate individuals than in literate controls ( Mohammadi et al, 2020 ). Some previous studies have suggested that the striatum may be more involved in reading in adults than in children.…”