Neglect dyslexia: A matter of "good looking"

Brain-damagedpatientswithright-sidedunilateralspatialneglect(USN)oftenmakeleft-sidederrorsin reading singlewordsorpseudowords(neglectdyslexia,ND).Weproposethatbothleftneglectandlow fixation accuracyaccountforreadingerrorsinneglectdyslexia. EyemovementswererecordedinUSNpatientswith(ND+) andwithout(ND) neglectdyslexiaand in amatchedcontrolgroupofrightbrain-damagedpatientswithoutneglect(USN). UnlikeND and controls, ND+ patients showedleftlateralizedomissionerrorsandadistortedeyemovementpatternin both areadingaloudtaskandanon-verbalsaccadictask.Duringreading,thetotalnumberof fixations waslargerinthesepatientsindependentofvisualhemispace,andmost fixations wereinaccurate. Similarly,inthesaccadictaskonlyND+ patients wereunabletoreachthemovingdot.Athird experimentaddressedthenatureoftheleftlateralizationinreadingerrordistributionbysimulating neglect dyslexiainND patients. ND and USN patients hadtoperformaspeededreading-at- threshold taskthatdidnotallowforeyemovements.Whenstimulusexplorationwasprevented,ND patients, butnotcontrols,producedapatternoferrorssimilartothatofND+ with unlimitedexposure time (e.g.,left-sidederrors). WeconcludethatneglectdyslexiareadingerrorsmayariseinUSNpatientsasaconsequenceofan additional andindependentdeficit unrelatedtotheorthographicmaterial.Inparticular,thepresenceof an alteredoculo-motorpattern,preventingtheautomaticexecutionofthe fine saccadiceyemovements involvedinreading,uncovers,inUSNpatients,theattentionalbiasalsoinreadingsinglecentrally presentedwords.