A PET study of word generation in Huntington's disease: effects of lexical competition and verb/noun category.
Huntington's disease (HD) patients show language production deficits that have been conceptualized as a consequence of executive disorders, e.g. selection deficit between candidate words or switching between word categories. More recently, a deficit of word generation specific to verbs has been reported, which might relate to impaired action representations in HD. We studied the brain correlates of language impairment in HD using H(2)O(15) positron emission tomography (PET). The activation task consisted of generation of semantically appropriate nouns and verbs in dominant (low lexical selection) and selective conditions (high lexical selection). Reaction times were longer and number of errors was higher in 12 non-demented HD than in 17 age-matched controls in all conditions. In both groups, the selective condition yielded longer reaction time and a greater number of errors than the dominant one. PET data revealed that, in control subjects, the left inferior temporal gyrus was involved in the selective condition whereas it was not in HD. Moreover, activity in the anterior cingulate and the inferior frontal gyri was correlated with behavioral performance in control subjects only. In HD, the lack of implication of these regions, already shown to be crucial in lexical selection, might have been partly compensated by the activation in the left supramarginal gyrus (phonological loop activity) and the right inferior frontal gyrus (effortful retrieval processes), which might support accessory language strategies allowing patients to achieve word generation.
Lepron
Evelyne
E
Inserm, Imagerie cérébrale et handicaps neurologiques UMR 825, F-31059 Toulouse, France. evelyne.lepron@inserm.fr
Péran
Patrice
P
Cardebat
Dominique
D
Démonet
Jean-François
JF
D000704:Analysis of Variance; D001921:Brain / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D001931:Brain Mapping; D005260:Female; D006801:Humans; D006816:Huntington Disease / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D007807:Language Tests; D008037:Linguistics; D008297:Male; D008606:Mental Processes / Q000502:physiology*; D008875:Middle Aged; D010104:Oxygen Radioisotopes; D049268:Positron-Emission Tomography; D011930:Reaction Time; D013647:Task Performance and Analysis; D014825:Vocabulary
D010104:Oxygen Radioisotopes