title: Neural and cognitive bases of upper limb apraxia in corticobasal degeneration.
abstract: OBJECTIVE
  To investigate the neural and cognitive bases of upper limb apraxia in corticobasal degeneration (CBD).
  
  
  METHODS
  Eighteen patients with CBD underwent a cognitive neuropsychological assessment of apraxia and resting [(18)F]-fluorodeoxyglucose PET scanning. Two complementary measures of apraxia were computed for each modality of gesture production. First, a performance score measured error frequency during gesture execution. Second, as a more stringent test of the integrity of the praxis system, the correction score measured the patient's ability to correct his or her errors on a second attempt. For each measure type, a cut-off score for the presence of apraxia was defined with regard to healthy controls. Using each cut-off score, the regional cerebral glucose metabolism of patients with CBD with apraxia (i.e., performing below cut-off score) was compared with that of patients with CBD without apraxia.
  
  
  RESULTS
  Mean performance scores were below normal values in all modalities. Anterior cingulate hypometabolism predominated in patients with CBD who performed below the cut-off performance score. At variance, mean correction scores were below normal values for gesture imitation only. Hypometabolism in superior parietal lobule and supplementary motor area characterized patients with CBD who were unable to correct their errors at the same rate as control subjects did.
  
  
  CONCLUSIONS
  Distinct neural networks underlie distinct aspects of the upper limb apraxic deficits in CBD. Extending previous findings of gesture production deficits in CBD, the use of complementary measures of apraxic behavior discloses a visuoimitative upper limb apraxia in CBD, underlain by a metabolic decrease in a parietofrontal neural network.
authors.affiliation: Centre de Recherches du Cyclotron, Service de Neuropsychologie, Université de Liège, Belgium. Philippe.Peigneux@ulg.ac.be
authors.forename: P
authors.initials: P
authors.lastname: Peigneux
authors.forename: E
authors.initials: E
authors.lastname: Salmon
authors.forename: G
authors.initials: G
authors.lastname: Garraux
authors.forename: S
authors.initials: S
authors.lastname: Laureys
authors.forename: S
authors.initials: S
authors.lastname: Willems
authors.forename: K
authors.initials: K
authors.lastname: Dujardin
authors.forename: C
authors.initials: C
authors.lastname: Degueldre
authors.forename: C
authors.initials: C
authors.lastname: Lemaire
authors.forename: A
authors.initials: A
authors.lastname: Luxen
authors.forename: G
authors.initials: G
authors.lastname: Moonen
authors.forename: G
authors.initials: G
authors.lastname: Franck
authors.forename: A
authors.initials: A
authors.lastname: Destee
authors.forename: M
authors.initials: M
authors.lastname: Van der Linden
mesh_terms: D000368:Aged; D001072:Apraxias / Q000000981:diagnostic imaging* / Q000378:metabolism; D001132:Arm; D003072:Cognition Disorders / Q000000981:diagnostic imaging* / Q000378:metabolism; D005260:Female; D005947:Glucose / Q000378:metabolism; D006801:Humans; D008297:Male; D008875:Middle Aged; D009044:Motor Cortex / Q000378:metabolism*; D010296:Parietal Lobe / Q000378:metabolism*; D014055:Tomography, Emission-Computed
chemical_list: D005947:Glucose