title: Effects of subthalamic deep brain stimulation on noun/verb generation and selection from competing alternatives in Parkinson's disease.
abstract: OBJECTIVE
  Impaired generation of verbs relative to nouns has been reported in Parkinson's disease (PD) and has been associated with the frontal pathophysiology of PD. The aim of the present study was to measure noun/verb generation abilities in PD and to determine whether noun/verb generation is affected by stimulation of the subthalamic nucleus (STN).
  
  
  METHODS
  8 participants who had been diagnosed with PD and had received surgery for deep brain stimulation (DBS) of the STN as well as 15 control participants completed a noun/verb generation task with four probe-response conditions-namely, noun-noun, verb-noun, noun-verb and verb-verb conditions. Patients with PD were assessed while receiving STN stimulation and without stimulation.
  
  
  RESULTS
  During the off stimulation condition, patients with PD presented with a selective deficit in verb generation compared with control participants. However, when receiving STN stimulation, patients with PD produced significantly more errors than controls during the noun-noun and verb-verb conditions, supporting evidence from previous studies that STN stimulation modulates a frontotemporal network associated with word generation. Finally, errors during verb generation were significantly correlated with item selection constraint (ie, the degree to which a response competes with other response alternatives) in the on stimulation condition, but not the off stimulation condition.
  
  
  CONCLUSIONS
  Our results suggest that STN stimulation affects the ability to select from many competing lexical alternatives during verb generation.
authors.affiliation: Centre for Research in Language Processing and Linguistics, Division of Speech Pathology, School of Health and Rehabilitation Sciences, The University of Queensland, Brisbane, Queensland, Australia.
authors.forename: J E
authors.initials: JE
authors.lastname: Castner
authors.forename: H J
authors.initials: HJ
authors.lastname: Chenery
authors.forename: P A
authors.initials: PA
authors.lastname: Silburn
authors.forename: T J
authors.initials: TJ
authors.lastname: Coyne
authors.forename: F
authors.initials: F
authors.lastname: Sinclair
authors.forename: E R
authors.initials: ER
authors.lastname: Smith
authors.forename: D A
authors.initials: DA
authors.lastname: Copland
mesh_terms: D000328:Adult; D000368:Aged; D046690:Deep Brain Stimulation; D005260:Female; D005625:Frontal Lobe / Q000503:physiopathology; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009415:Nerve Net / Q000503:physiopathology; D010300:Parkinson Disease / Q000503:physiopathology / Q000628:therapy*; D012660:Semantics; D013067:Speech Perception / Q000502:physiology; D013068:Speech Production Measurement; D020531:Subthalamic Nucleus / Q000503:physiopathology*; D013702:Temporal Lobe / Q000503:physiopathology; D014705:Verbal Behavior / Q000502:physiology*