%0 Journal Article
%T Endophenotype Approach to Developmental Dyslexia: Neurogenetic, Neurobiological, and Neurocognitive
%A Sema Acar
%J -
%D 2018
%X Developmental dyslexia is a neurodevelopmental disorder characterized by unexpected problems in learning to read, fluent reading, and reading comprehension in spite of age-appropriate IQ level, education, and environmental opportunities (D¨¦monet, Taylor & Chaix, 2004; Vellutino, Fletcher, Snowling & Scanlon, 2004). Fluent reading and reading comprehension require rapid, successive and/or parallel activation and effective communication of multiple brain circuits. Brain ¡°reading¡± circuits are sustained by multiple and distant neuronal networks which are also involved in language, visual, and orthographic processing, in addition to attention, 1 £¿£¿r. G£¿r., Ba£¿kent ¨¹niversitesi, Odyoloji B£¿l¨¹m¨¹, semaacar@baskent.edu.trexecutive functions, and higher level cognition processing (Norton & Wolf, 2012). However, genetically driven structural and functional differences in these brain circuits might cause problems in these neurocognitive abilities in developmental dyslexia. Therefore, individuals diagnosed with developmental dyslexia or with familial risk might have problems in reading related cognitive, sensorial, and language abilities such as phonological working memory, processing of rapid auditory/visual stimuli, phonological awareness, and rapid automatized naming (see Vellutino et. al., 2004, for a review). In addition, problems in motor coordination and balance are commonly reported (Rochelle & Talcott, 2006). As a consequence of heterogeneity in the clinical profile, various theories have been postulated to explain the underlying mechanisms of the disorder: The Phonological Deficit Theory suggests that problems in phonological awareness, rapid automatized naming, and phonological working memory are indeed the underlying reasons of developmental dyslexia, since these abilities are fundamental to reading development. The theory suggests that the problems in these abilities might be due to the perisylvian cortex dysfunction (Kovelman et. al., 2012). In addition, some researchers propose Double-Deficit Hypothesis. According to which, rapid automatized naming and phonological abilities are closely related with each other but mediated by independent sub-mechanisms. Therefore, individuals having disorders in both might have more severe reading problems (Nelson, 2015). On the one hand, Magnocelluar Theory suggests that the underlying reason of the developmental dyslexia is the synchronization and integration of the rapid visual and auditory stimuli due to medial thalamic and geniculate nucleus abnormalities (Stein & Walsh, 1997). On the other hand, Cerebellar
%K geli£¿imsel disleksi
%K endofenotipik yakla£¿£¿m
%K disleksi aday genleri
%K dorsal-ventral-anterior okuma a£¿lar£¿
%K fonolojik fark£¿ndal£¿k
%K h£¿zl£¿ otomatik isimlendirme
%K i£¿leyen bellek
%U http://dergipark.org.tr/dkyad/issue/44794/557203