Authors: Ohad Nachshon, Rola Farah, and Tzipi Horowitz-Kraus.
Publication: Frontiers in Human Neuroscience (Frontiers). Vol 14, p 104 2020 | DOI: 10.3389/fnhum.2020.00104
Introduction: Dyslexia is a reading disorder characterized by significant difficulty in reading, as well as reports of altered executive functions (EF). Children with reading difficulties (RD) experience a broad range of social and emotional problems. Recently it was suggested that children with RD have altered functional connections within the amygdala, which is related to emotional processing. Altered brain laterality related to reading was previously reported in children with RD. Hence, we sought to determine the differences in functional connectivity between the right and left emotional network as related to emotional challenges and the other reported difficulties in reading and EF in children with RD compared to typical readers.
Methods: Sixty-four 8 to 12 year old children, 27 children with RD and 37 age-matched typical readers, participated in the study. Reading, emotional, and EF abilities were assessed. Global efficiency of the emotional network was calculated and compared between the groups, and left vs. right functional connectivity of the amygdala was tested using the CONN toolbox. Functional connectivity measures were then associated with measures of reading, emotional, and EF abilities.
Results: Children with RD showed significantly decreased emotional and EF abilities compared to typical readers. A negative correlation between reading, emotional, and EF abilities was determined in both groups. Neuroimaging results showed decreased global efficiency measures within the emotional network in children with RD, who also showed lower functional connectivity between the amygdala and the left and right frontal pole regions. Results also indicated increased functional connectivity of the right vs. left amygdala with left and right pre-central and post-central gyri regions, which were related to decreased reading, emotional, and EF abilities in both typical readers and children with RD.
Conclusion: The positive relationship between EF and emotional abilities in children with RD strengthens the relationship between EF difficulties and emotional stress, which in turn may lower EF abilities (monitoring, inhibition, and attention) as well as decreased reading abilities. The emotional challenges in children with RD were associated with decreased functional connectivity of the left amygdala with pre/post central gyrus and cognitive-control regions. These findings suggest that although the right hemisphere is thought to be related to emotional stress, it was the decreased control of the left hemisphere that was related to emotional disturbance in children with RD.
– Decreased emotional and cognitive control abilities and the relationship between these abilities in children with RD vs. typical readers.
– Decreased global efficiency of the emotional network during rest in children with RD vs. typical readers, related to lower emotional abilities.
– Increased functional connectivity between the left vs. right amygdala and the right frontal pole, and between the left amygdala and the left frontal pole in typical readers compared to children with RD.
– Increased functional connections between the left vs. right amygdala in typical readers compared to children with RD, related to better cognitive control, and emotional and reading abilities.
“our results suggest that the global efficiency of the amygdala is decreased in those with RD compared to typical readers, and that the left and right amygdala contribute to reading, emotional, speed of processing and EF abilities in an unequal manner; i.e., greater functional connections between the left vs. right amygdala and frontal cortices were related to increased reading, emotional, speed of processing and EF abilities. Therefore, for the first time, we have demonstrated a linkage between the laterality of the amygdala functional connectivity and frontal regions and reading, emotional and EF abilities.”