Spectrograms of a natural speech stimulus <i>zizul</i> (A) and its nonspeech counterpart (B).

<p>Spectrograms of a natural speech stimulus <i>zizul</i> (A) and its nonspeech counterpart (B).</p

Speech-nonspeech discrimination.

<p>(A) Discrimination (d′) by dyslexics and skilled readers (controls). (B) The sensitivity of dyslexics and controls to the phonological structure of Hebrew stems in a speech discrimination task (Error bars are confidence intervals for the difference between the means).</p

Phonetic identification of consonants and vowels by skilled readers and dyslexics along a 10-step continuum.

<p>Step continuum denotes the target stimulus. Error bars reflect confidence intervals for the difference between the group means.</p

Accuracy (proportion errors) of skilled and dyslexic participants in speech/nonspeech discrimination (Experiment 2).

<p>Accuracy (proportion errors) of skilled and dyslexic participants in speech/nonspeech discrimination (Experiment 2).</p

Reading scores of dyslexic and control participants in Experiments 1–3.

<p>Reading scores of dyslexic and control participants in Experiments 1–3.</p

Word/nonword discrimination. (

<p>A) Discrimination (d′) by dyslexics and skilled readers (controls). (B) The sensitivity of dyslexics and controls to the phonological structure of Hebrew stems in the discrimination of auditory nonwords from words (Error bars are confidence intervals for the difference between the means).</p

Accuracy (proportion errors) of skilled and dyslexic participants in word/nonword discrimination (Experiment 1).

<p>Accuracy (proportion errors) of skilled and dyslexic participants in word/nonword discrimination (Experiment 1).</p

Phonetic discrimination of consonants and vowels by skilled readers and dyslexics along a 10-step continuum.

<p>Step continuum denotes the midpoint between the two stimuli (A and B) presented for discrimination. Error bars reflect confidence intervals for the difference between the group means.</p

Position of Neocortical Neurons Transfected at Different Gestational Ages with shRNA Targeted against Candidate Dyslexia Susceptibility Genes

<div><p>Developmental dyslexia is a language learning disorder that affects approximately 4–10% of the population. A number of candidate dyslexia susceptibility genes have been identified, including <i>DCDC2</i> and <i>KIAA0319</i> on Chromosome (Chr) 6p22.2 and <i>DYX1C1</i> on Chr 15q21. Embryonic knockdown of the function of homologs of these genes in rat neocortical projection cell progenitors by <i>in utero</i> electroporation of plasmids encoding small hairpin RNA (shRNA) revealed that all three genes disrupted neuronal migration to the neocortex. Specifically, this disruption would result in heterotopia formation (<i>Dyx1c1</i> and <i>Kiaa0319</i>) and/or overmigration past their expected laminar location (<i>Dyx1c1</i> and <i>Dcdc2</i>). In these experiments, neurons normally destined for the upper neocortical laminæ were transfected on embryonic day (E) 15.5, and we designed experiments to test whether these migration phenotypes were the result of targeting a specific type of projection neuron. We transfected litters with <i>Dcdc2</i> shRNA, <i>Dyx1c1</i> shRNA, <i>Kiaa0319</i> shRNA, or fluorescent protein (as a control) at each of three gestational ages (E14.5, E15.5, or E16.5). Pups were allowed to come to term, and their brains were examined at 3 weeks of age for the position of transfected cells. We found that age of transfection did not affect the percentage of unmigrated neurons—transfection with <i>Kiaa0319</i> shRNA resulted in heterotopia formation at all three ages. Overmigration of neurons transfected with <i>Dcdc2</i> shRNA, while present following transfections at the later ages, did not occur following E14.5 transfections. These results are considered in light of the known functions of each of these candidate dyslexia susceptibility genes.</p></div