Abnormal attentional internetwork link in dyslexic readers

Objective: Attention ability can be divided into three separate networks (executive, orienting, and alerting) that differ in their function and neurobiology. It has been suggested that the right temporal parietal junction (TPJ) can gate between the orienting and the alerting systems. Because there is converging evidence suggesting that the right TPJ functions abnormally in dyslexia, the current work examines behaviorally the independence of the orienting and the alerting systems in dyslexic readers. Method: The Attention Network Test (ANT) is a nonlinguistic test designed to measure behaviorally the separate attention systems using a single test. One feature of the ANT test is that it captures the separability and independence of the normal attention networks. In the current study, dyslexic readers preformed the ANT test and their performance was compared with normal readers. Results: Here we demonstrate, consistent with previous theories, impairment in executive and orienting networks in dyslexic readers; however, for the first time, we reveal unique situations in which the orienting spatial attention system in dyslexia is abnormally dependent on and negatively correlated with the alerting attention system. Conclusions: Dyslexics suffer from globally spread abnormal nonlinguistic attentional networks in what are considered separate attentional systems in the normal population; it appears that they are abnormally interrelated in the dyslexic population.