title: Converging evidences on language impairment in Landau-Kleffner Syndrome revealed by behavioral and brain activity measures: a case study.
abstract: OBJECTIVE
  To assess the linguistic abilities of a boy having Landau-Kleffner Syndrome, and relate the focal disturbance of brain activity due to epilepsy to the cognitive and linguistic deficits.
  
  
  METHODS
  Several kinds of assessments were carried out, including epileptic source analysis using electronic source localization methods and PET, neuropsychological assessment of cognitive functions, and assessment of speech perception skills (discrimination of phonetic and stress cues) using ERPs.
  
  
  RESULTS
  The source of epileptic activity was localized in the left superior temporal lobe. The neuropsychological assessment showed dissociation between verbal and nonverbal functions, and the performance in former was bellow the normal range. ERPs obtained to the processing of phonetic and stress speech cues indicated that the two cues were processed asymmetrically: the mismatch negativity component (MMN) was obtained for the phoneme difference, but not for the stress pattern difference.
  
  
  CONCLUSIONS
  Our data converged as it showed that the patient presented a selective impairment of the language system, and the verbal working memory system appeared to be especially defective. It is suggested that the language deficit is at least partly due to the focal disturbance of those neural networks that underlie the functioning of the working memory system.
  
  
  CONCLUSIONS
  LKS is a childhood language disorder that might serve as a model in studying what happens to the language system if, in the course of development, the essential neural circuits are severely disturbed.
authors.affiliation: Research Institute for Psychology, Hungarian Academy of Sciences, Department of Psychophysiology, Research Group of Developmental Psychophysiology, H-1068, Szondi u. 83-85, Budapest, Hungary. hf@cogpsyphy.hu
authors.forename: Ferenc
authors.initials: F
authors.lastname: Honbolygó
authors.forename: Valéria
authors.initials: V
authors.lastname: Csépe
authors.forename: Attila
authors.initials: A
authors.lastname: Fekésházy
authors.forename: Miklós
authors.initials: M
authors.lastname: Emri
authors.forename: Teréz
authors.initials: T
authors.lastname: Márián
authors.forename: Gergely
authors.initials: G
authors.lastname: Sárközy
authors.forename: Rozália
authors.initials: R
authors.lastname: Kálmánchey
mesh_terms: D001931:Brain Mapping; D002648:Child; D003071:Cognition / Q000502:physiology; D004569:Electroencephalography / Q000379:methods; D005072:Evoked Potentials, Auditory / Q000502:physiology*; D006801:Humans; D018887:Landau-Kleffner Syndrome / Q000150:complications*; D007805:Language Development Disorders / Q000209:etiology*; D007807:Language Tests / Q000706:statistics & numerical data; D008037:Linguistics; D008297:Male; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D049268:Positron-Emission Tomography / Q000379:methods; D012890:Sleep / Q000502:physiology; D013067:Speech Perception / Q000502:physiology; D013702:Temporal Lobe / Q000473:pathology / Q000503:physiopathology*; D014851:Wakefulness / Q000502:physiology