Towards an understanding of the role of the ‘magnocellular advantage’ in fluent reading

Reading disability is a relatively common developmental disorder, the aetiology of which is clouded by conflicting theoretical approaches and the heterogeneity of the subtypes found. Recent advances in understanding of the visual system have revived interest in the role of visual processing in the persisting inability to read fluently that characterises dyslexia. A new integrated model of visual processing based on primate single cell and human electrophysiology may provide such a framework, implicating the magnocellular pathway's role in activating and driving attentional mechanisms in higher order cortical regions. In particular, the recent introduction of transcranial magnetic stimulation (TMS) to create ‘transient lesions’ may provide causal evidence for dorsal stream feedforward/feedback involvement in rapid visual processing tasks. Such organization is argued to be crucial for the development of fluent reading.