Testing for visual agnosia. Bedside cognitive tests include object naming and ability to provide semantic information about unnamed items. Visuo-perceptual ...SkiptomaincontentYouarehereHomeArchiveVolume76, Issuesuppl5Apraxia,agnosias,andhighervisualfunctionabnormalitiesEmailalertsArticleTextArticlemenuArticleTextArticleinfoCitationToolsShareRapidResponsesArticlemetricsAlertsPDFApraxia,agnosias,andhighervisualfunctionabnormalitiesFreeJDWGreeneCorrespondenceto:
DrJohnDWGreene
SouthernGeneralHospital,InstituteofNeurologicalSciences,1345GovanRoad,Glasgow,G514TF,UK;john.greenesgh.scot.nhs.ukhttp://dx.doi.org/10.1136/jnnp.2005.081885StatisticsfromAltmetric.comapraxiaagnosiashighervisualfunctionabnormalitiesdisconnectionsyndromesCognitiveneurologydealsmainlywithdisordersofmemory(forexample,isthepatient’spoormemoryduetoearlydementiaortoanxiety/depression?)orlanguage(asinstroke).Itshouldberemembered,however,thatotherareasofcognitionmaybeselectivelyimpaired.Thisreviewwillcoverdisordersofperceptionandofhigherordermotoroutput,bothintermsofpathologicallossandpathologicalgainoffunction.PERCEPTIONANDITSDISORDERSApatientmustbeconsciousinordertoperceivetheworldaroundthem.Anexplorationofconsciousnessisoutsidetheremitofthisarticlethoughrecentlyreviewedbyothers.1,2Thepatientmustalsohavethecapacitytoattendselectivelyinordertofocusononepartofthesensorium.Perceptualprocessingisthennecessarytoidentifywhatisbeingperceivedthroughthevarioussensorymodalities(namelyvision,hearing,touch,smell,taste),thusallowingaccesstosemanticknowledgeandthroughthisunderstandingoftheenvironment.Initially,perceptualinformationisbasicandmodalityspecific,butasitisprocessedbyhigherordercentres,meaningisascribedtopercepts,andinformationbecomesmulti-modal(fig1).Ultimately,semanticknowledgeisaccessedusingthevarioussensorystreams.Forexample,ifstandinginthepathofanoncomingtrain,basicperceptionwillinvolvevisualinformation,hearingthetraincoming,andfeelingvibrationfromtheground.Theseseparatestreamsthencometogether,accessi