title: Deficits in inhibitory control and conflict resolution on cognitive and motor tasks in Parkinson's disease.
abstract: Recent imaging studies in healthy controls with a conditional stop signal reaction time (RT) task have implicated the subthalamic nucleus (STN) in response inhibition and the pre-supplementary motor area (pre-SMA) in conflict resolution. Parkinson's disease (PD) is characterized by striatal dopamine deficiency and overactivity of the STN and underactivation of the pre-SMA during movement. We used the conditional stop signal RT task to investigate whether PD produced similar or dissociable effects on response initiation, response inhibition and response initiation under conflict. In addition, we also examined inhibition of prepotent responses on three cognitive tasks: the Stroop, random number generation and Hayling sentence completion. PD patients were impaired on the conditional stop signal reaction time task, with response initiation both in situations with or without conflict and response inhibition all being significantly delayed, and had significantly greater difficulty in suppressing prepotent or habitual responses on the Stroop, Hayling and random number generation tasks relative to controls. These results demonstrate the existence of a generalized inhibitory deficit in PD, which suggest that PD is a disorder of inhibition as well as activation and that in situations of conflict, executive control over responses is compromised.
authors.affiliation: Cognitive-Motor Neuroscience Group, Sobell Department of Motor Neuroscience and Movement Disorders, UCL Institute of Neurology, The National Hospital for Neurology and Neurosurgery, 33 Queen Square, London, WC1N 3BG, UK.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Obeso
authors.forename: Leonora
authors.initials: L
authors.lastname: Wilkinson
authors.forename: Enrique
authors.initials: E
authors.lastname: Casabona
authors.forename: Maria Luisa
authors.initials: ML
authors.lastname: Bringas
authors.forename: Mario
authors.initials: M
authors.lastname: Álvarez
authors.forename: Lázaro
authors.initials: L
authors.lastname: Álvarez
authors.forename: Nancy
authors.initials: N
authors.lastname: Pavón
authors.forename: Maria-Cruz
authors.initials: MC
authors.lastname: Rodríguez-Oroz
authors.forename: Raúl
authors.initials: R
authors.lastname: Macías
authors.forename: Jose A
authors.initials: JA
authors.lastname: Obeso
authors.forename: Marjan
authors.initials: M
authors.lastname: Jahanshahi
mesh_terms: D003071:Cognition / Q000502:physiology*; D003220:Conflict, Psychological; D005260:Female; D006801:Humans; D007266:Inhibition, Psychological; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D010300:Parkinson Disease / Q000503:physiopathology* / Q000523:psychology; D011597:Psychomotor Performance / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology; D057190:Stroop Test; D020531:Subthalamic Nucleus / Q000503:physiopathology