Dyslexia as an adaptation to cortico-limbic stress system reactivity

Kershner, John R.

doi:10.1016/j.ynstr.2020.100223

Cited by 16 publications

(21 citation statements)

References 121 publications

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“…Assuming this to be relatively well-established, a salient issue in the dyslexia puzzle becomes the identification of the experiential and heritability circumstances that undermine the developmental integrity of the brain’s attentional networks. The current Evo-Devo model proposes that the evolutionary selection for the timing of neuroplasticity in early childhood is a key organizing biological principle in dyslexia ( Kershner, 2020a ). Plasticity, defined as reorganizational capabilities in neuronal circuits and behavior in response to patterns of sensory inputs, is an essential requirement for learning to read ( Vandermosten et al, 2016 ).…”

Section: Brain Oscillations Attentional Network and Stress System mentioning

confidence: 99%

“…Recent theoretical advances in evolutionary developmental biology (Evo-Devo) question the justifiability of applying these assumptions widely to the general population. Evo-Devo models of stress and dyslexia, showing how early stress may lead to costly but adaptive behavioral strategies in the course of growing up, suggest that stress responsivity is not abnormal or strictly dysfunctional ( Ellis and Del Giudice, 2019 ), although stress system dysregulation may result in children struggling to acquire fluent reading skills ( Kershner, 2019 , 2020a ). Such conditional during typical child development contradicts the view sometimes exhibited in research and clinical studies that individuals with dyslexia are suffering from a pathopsysiological condition.…”

Section: Introductionmentioning

confidence: 99%

“…The significance of this to Evo-Devo and dyslexia is that the HPA and LC/NE systems are stress reactive and, within normal limits, produce considerable interindividual response variability ( Krugers et al, 2017 ; Ellis and Del Giudice, 2019 ; Schultz et al, 2019 ). Their combined recruitment, even under mild chronic stress, has the potential to produce excessive levels of glucocorticoids, which cross the choroid plexus blood-brain barrier, and norepinephrine, which together may (1) bias the stress/cognitive growth balance in favor of stress management, and (2) upset the homeostatic balance of processing among the major brain networks involved in beginning and fluent reading ( Kershner, 2020a ). Recent research in dyslexia is consistent with this hypothesis.…”

Section: Introductionmentioning

confidence: 99%

“…This paper draws on recent experimental research in neuroscience to refine the normal-variability Evo-Devo model of dyslexia ( Kershner, 2020a ), and to extend the scope of discussion in considering the validity of the model. The first section outlines this perspective, which focuses on the connection between stress and dyslexia, in the broader context of the medical model orientation that has framed the scope of research and perhaps had a limiting influence on educational efforts in dyslexia over the last decades.…”

Section: Introductionmentioning

confidence: 99%

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An Evolutionary Perspective of Dyslexia, Stress, and Brain Network Homeostasis

Kershner

2021

Front. Hum. Neurosci.

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Evolution fuels interindividual variability in neuroplasticity, reflected in brain anatomy and functional connectivity of the expanding neocortical regions subserving reading ability. Such variability is orchestrated by an evolutionarily conserved, competitive balance between epigenetic, stress-induced, and cognitive-growth gene expression programs. An evolutionary developmental model of dyslexia, suggests that prenatal and childhood subclinical stress becomes a risk factor for dyslexia when physiological adaptations to stress promoting adaptive fitness, may attenuate neuroplasticity in the brain regions recruited for reading. Stress has the potential to blunt the cognitive-growth functions of the predominantly right hemisphere Ventral and Dorsal attention networks, which are primed with high entropic levels of synaptic plasticity, and are critical for acquiring beginning reading skills. The attentional networks, in collaboration with the stress-responsive Default Mode network, modulate the entrainment and processing of the low frequency auditory oscillations (1–8 Hz) and visuospatial orienting linked etiologically to dyslexia. Thus, dyslexia may result from positive, but costly adaptations to stress system dysregulation: protective measures that reset the stress/growth balance of processing to favor the Default Mode network, compromising development of the attentional networks. Such a normal-variability conceptualization of dyslexia is at odds with the frequent assumption that dyslexia results from a neurological abnormality. To put the normal-variability model in the broader perspective of the state of the field, a traditional evolutionary account of dyslexia is presented to stimulate discussion of the scientific merits of the two approaches.

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Section: Brain Oscillations Attentional Network and Stress System mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An Evolutionary Perspective of Dyslexia, Stress, and Brain Network Homeostasis

Kershner

2021

Front. Hum. Neurosci.

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“…Recently, dyslexia was suggested as a coping response to environmental challenges [31]. In 2016, the prevalence of dyslexia was estimated to be 5-17% in the United States [32], however, no definitive answer has been found [33].…”

Section: Introductionmentioning

confidence: 99%

Potential Logographic Dyslexics Identified via Self-Reporting during a Questionnaire Survey in Taiwan

Sun¹,

Liao²

2021

Dyslexia

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According to the patterns of difficulties of the dyslexics that have been reported in Western societies, a questionnaire in traditional Chinese was developed to carry out initial screening among Taiwanese. The questionnaire includes 30 items with four-point scales and 7 open-ended questions. Of the 2133 copies distributed, a total of 1599 questionnaires were collected which gives a 75.0% response rate and 1442 were completed. The mean of 30-item scores collected from 1442 participants is 87.99 ± 11.9. Among these participants, 9 self-reported potential logographic dyslexics have been identified. The individual scores of 30 items of the nine subjects were at least 1 SD to 4.5 SD lower than that of their counterparts. There are two potential logographic dyslexics families show genetic influence. Since there is no standard test for dyslexics, we developed a 30-item questionnaire that can be completed in 15-20 minutes on average. The questionnaire may serve as a low cost, initial screening tool and allows the potential probands to self-report while the formal diagnosis is not available.

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Elevated unanticipated acoustic startle reactivity in dyslexia

Palser,

Veziris,

Morris

et al. 2024

Dyslexia

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People with dyslexia, a neurodevelopmental disorder of reading, are highly attuned to the emotional world. Compared with their typically developing peers, children with dyslexia exhibit greater autonomic nervous system reactivity and facial behaviour to emotion‐ and empathy‐inducing film clips. Affective symptoms, such as anxiety, are also more common in children with dyslexia than in those without. Here, we investigated whether the startle response, an automatic reaction that lies at the interface of emotion and reflex, is elevated in dyslexia. We measured facial behaviour, electrodermal reactivity (a sympathetic nervous system measure) and emotional experience in response to a 100 ms, 105 dB unanticipated acoustic startle task in 30 children with dyslexia and 20 comparison children without dyslexia (aged 7–13) who were matched on age, sex and nonverbal reasoning. Our results indicated that the children with dyslexia had greater total facial behaviour and electrodermal reactivity to the acoustic startle task than the children without dyslexia. Across the sample, greater electrodermal reactivity during the startle predicted greater parent‐reported anxiety symptoms. These findings contribute to an emerging picture of heightened emotional reactivity in dyslexia and suggest accentuated sympathetic nervous system reactivity may contribute to the elevated anxiety that is often seen in this population.

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Dyslexia as an adaptation to cortico-limbic stress system reactivity

Cited by 16 publications

References 121 publications

An Evolutionary Perspective of Dyslexia, Stress, and Brain Network Homeostasis

An Evolutionary Perspective of Dyslexia, Stress, and Brain Network Homeostasis

Potential Logographic Dyslexics Identified via Self-Reporting during a Questionnaire Survey in Taiwan

Elevated unanticipated acoustic startle reactivity in dyslexia

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